Double period

So this month my period was from the 7th to the 9th, the 10th was just spotting. I was on the Nuvaring, and that was my week off. The 11th was the day I had to put it back on, but my Dr. changed me to the low estrogen pill. This week I got a stomach bug (vomits, diarrhe, fever, body aches) the 16th, that's still going on. The 17th I started spotting, and the 18th I started a heavy flow. So my question is, getting my period for a 2nd time this month something normal when you change pills or it might be something else?