Anyone know what this could be?

**I am making a doctor's appointment Monday morning, I'm just curious to what you guys think** So for about 2 days now I've been getting these little pains in my stomach followed by an undescribable feeling. It'll stop for a minute and come right back, constantly. Today I started having diarrhea also. I just ended my period so it's not PMS. Also, I'm not sure if this is even relevant but my period came about a week late and was very light the whole time and ended 2 days early. (I always have a 7-10 day period and it only lasted for 5) **I know that your not a doctor, I just want to know if anyone else has had this happen &if; so, what was it?)**