I am lactose intolerant and recently visited my girlfriend's home over spring break, so my diet changed a little bit. They eat lots of meat, lots of carbs, lots of dairy. Normally, I only eat rice and fish. This all happened when we came home from that vacation.

The past week so far I've had excessive gas and diarrhea-like cramps. When I go to the bathroom, there's a lot of flatulence, but only a small amount of stool. It's yellow in color and it has the consistency of constipation almost. It's solid and dense, yet it floats. One time, though, it became watery and was accompanied with very painful cramps that felt like it was burning my lower abdomen. Yellowish mucus is visible as well. 

I've tried eliminating dairy from my diet for one day to see if that would help, but nothing changed. I still had these symptoms. I do not take any medication, but I do take lactase pills when I'm eating out. Also, I took Excedrin Extra Strength 2 weeks ago to help with my period cramps. My colleagues tell me that it's probably just stress form school, but I don't know. 

Please help me.