The predictor

Unlike everyone else, my sure predictor that I'll be having my monthly period is severe hyperacidity.
The moment I felt that I'm extremely acidic, I will just have to wait for an hour and then voila! It's already there.
I have been looking up for possible reason for this but I am yet to find the answer.
This morning, I got snoozed the alarm up until at 6:30 AM. I'm feeling acidic already but I took cold shower anyway. I was still in bathrobe and my hair was still pulled up in towel when I felt surge of acid in my gut.
I lied down for a while and next thing I know was my sister knocking on my door. It was already past 9:00 am and they were wondering why I have not gotten out yet of my room since it usually takes me about 30 minutes to dress up after bathing. I dozed off, I guess because of the pain.
I was supposed to go to school but I took a raincheck instead and rested until 10:30 this morning.
The acidity went a little off when I woke up. I was able to make it to work though a bit late.I popped an antacid because....I need to get my daily fix of caffeine.
Now I feel a whole lot better.
It's good that it struck today because tomorrow is the live lecture on pharmacology. Today was computer based which I can catch up on anytime.