Open Question: Two periods? IM THINKING ITS STRESS.?

I had sex on july 16th, and we were protected with a condom and he pulled out. I had a some bleeding when my period was suppose to arive but it was like a week early, it started Aug 3rd and should start on the 6th or so. This lasted for five days and was super light. Well yeasterday I started a pretty heavy flow and i have major cramps. What does this mean. I also had surgery on my nose on the tenth and I had to take a preg test and it came out neg. I have no symptoms what so ever of being preg. Also I have been under alot of stress. My mom had a heart attack last week and was fierd from work. I started my senior year too. Im thking all of this is due to stress. Any answers are helpful except negative ones cuz this is serious!!! Thank you!