Birth control, nausea, and early period?

First off, I have very safe sex, so the chances of me being pregnant are about 0.01%. I'm on the pill and take it exactly as directed and my partner and I also use condoms.

I've been on the same birth control for a little over a year now, and I've never, ever gotten my period on any day other than Sunday for a year or so. A few days before my expected period I had some discharge with some brown spotting, not even enough spotting to stain or anything, a very minimal amount. That's never happened to me before my period. However today I got my period a day early. Since its only a day early, I'm not really concerned, but since I always take the pill exactly as directed, with an alarm every day and everything, it was a little weird. Concerned I took a pregnancy test today (the day I started my period) just because I'm an extremely paranoid person, and it came up negative as expected.

I was having some cramping and nausea about two days before I got my period, I also have irritable bowel syndrome so I mostly chalked it up to that, took some miralax, and that problem was solved.

However today I was at work, and wasn't feeling so hot. I ended up getting ill and throwing up and got sent home. I hadn't had anything to drink all day except half a can of diet rootbeer, so I chalked that up to dehydration.

Now, I'm on my period, and have minor cramps, which is normal to me.

I guess I'm just concerned if all of these things in the past few days are all separated incidents, or if they could be related somehow? Any input helps. Thanks!