D*, and my exams start tomorrow!! Help!

[BarnOwl]

I was revising for my biology exam (which is tomorrow, the start of my GCSEs) and my lower abdomen started to really hurt on and off. After about an hour of this, I went to the toilet and (sorry!) it was very loose and fluffy. Oh shit, literally.

5 minutes after my mum drove me to the local shop. I bought 2 packet of Immodium and some antacids. I am prepared. Or so I thought.

We then drove down the road to the mcdonald's drive thru because mum wanted to get her dinner from there. When I got my drink, I took 2 immodiums like the packet says I should and I got really dizzy. Everything went weak and I started to really panic. Just got back now (it's 2 minutes away from my house in the car) and my arms are achy and heavy and my head hurts (my tummy does to) and i'm shaking (anxiety) and... i really don't want to v* not now, not ever, but especially not now. gcses start tomorrow.

Is it PMS? IBS (ever though this has never happened before with my ibs). Combination of the 2 (day 18 on cycle). Something I ate? I did have one bite of a shady sausage sandwich like 7 hours ago. I am praying to an unknown deity that this isn't an sv. What is this?

As I said, final exams start tomorrow. I wasn't really worried about it ..until now! D: