The final straw came two cycles ago.

Everyone and everything had been annoying me for a few weeks. Lockdown isn’t easy for any of us, but my patience had gone out the window.

I was barking at my partner, Alex, for leaving the tea towel on top of the bench and blasting my mum for texting me pointless messages. I was basically sweating ALL of the small stuff.

I hated myself, and this was just not me. I knew my period was due and I put it down to PMT, which every woman gets to some degree... right?

Watch: If a man lived like a woman for a day. Post continues below.

No matter how much meditation I did, nothing seemed to help.

Negative thoughts were constantly creeping into my head while I was trying to sleep.

They were mostly about me not being good enough for my partner and that he was obviously going to leave me, that I was a shit mum and there was no point writing a book (which I was negotiating with a publisher - my dream come true!) because no one was going to read it.

I had no motivation for anything. Even the agreement with the publisher and deadline for submission didn't spark excitement in me.

Who even was I?

It was relentless. I hated myself, I hated my partner, I hated everything.

I’d gone from irritated to uncontrollable anger in a matter of hours. I picked a fight with Alex that escalated and I turned into a screaming, raging lunatic. I saw red; there was just no stopping me.

I stormed upstairs and flopped on the bed. Anger turned into sadness. I was a blubbering mess; so much so that I couldn’t catch my breath. I didn't want to be here anymore. I just wanted it to stop.

Alex came up and found me in the fetal position. He rubbed my back and helped me to breathe, saying "Babe, this isn’t ok, we’ve got to do something about this."

The next day I started bleeding, and like a switch, I was back to my normal self. It was like I had two completely different personalities: one in the lead-up to my period and one as soon as it landed.

Alex wasn’t the only victim of my problematic behaviours. My mum stormed out of our place after filmingGoggleboxand said, "You’re being an absolute bitch, I cannot be around you like this!"

Little did I know mum and Alex started confiding in one another, as they were genuinely concerned about my mental health. One minute I would be happy, relaxed Isabelle and the next, a total tyrant.

Fortunately for me, mum heard an interview with a clinical psychologist on the radio talking about a newly recognised disorder called PMDD (Premenstrual Dysphoric Disorder).

I’d never heard of it, but the next thing I knew, I found a printed out explanation left on my pillow. Hmmm, subtle.

When I picked up the paper and read the symptoms, I actually couldn’t believe it.

Suddenly, everything made sense. I ticked every box: sadness, irritability, anxiety, rages, paranoia, sensitivity, fatigue, negative thoughts. OMG, this was ME - but literally only between ovulation and getting my period.

I felt instantly empowered, and it was reassuring that I wasn’t actually completely mad.

Was this a possible explanation for my feelings and behaviour? I wanted answers... why, and how, and what could I do about it?

On this episode of The Quicky, we unpack PMDD - the period condition that's ruining lives. Post continues below.

I always take a very thorough approach when it comes to my health, and I won't stop until I investigate everything in detail.

I went straight to my GP and got a referral for an appointment to see a specialist at the Jean Hailes Clinic, a women’s health facility in Melbourne.

Meanwhile, I did some tests to try and get an idea of where my body was at.

My blood results came back low in iron, B12 and zinc, and I started to wonder if maybe my gut was out of whack.

I’ve had a history of cancer polyps in the past, so staying on top of my gut health is high on my priority list. I pooed into a cup and sent it off for a full microbiome mapping test which was all guided by my dietician.

Turned out I had an unwelcome friend, a parasite, who had been hanging in there for god knows how long and eating all my good stuff like iron, B12 and zinc.

Nothing that strong antibiotics couldn’t fix, but could this be contributing to how my body processed my hormones?

The day I had my appointment with Dr Lee Mey Wong at the Jean Hailes Clinic was the day my life changed forever.

I explained to her that there are days I just want to lie in bed and cry, and that I feel annoyed and irritated by my partner simply breathing near me. There are times where I ignore my friends’ messages and calls and don’t reply back to emails.

I feel overwhelmed and like I just have no motivation. I feel anxious and insecure in my relationship and start acting like a paranoid, crazy woman. Not just thinking things but acting on them. The urge just takes over me with no rational thinking.

We established the timeline of my symptoms - even my enormous and sore boobs that make me feel like aPlayboycentrefold.

I discovered that PMDD rears its ugly head during the ‘luteal phase’ which, if you’re like me and have no idea what that means, is the time between ovulation and bleeding.

"There’s no doubt in my mind that you have PMDD," Dr Wong said. She was so calm, so caring and full of such fascinating knowledge. I took a big, deep breath.

"But why?" I asked. "What does this mean?" Here I was, 36 years old, I’d been having my period for years now and birthed one child. How the hell did it take this long to figure it out?