I had an appendectomy about 2 and a half weeks ago, i have had rather severe diarrhea for the past 3 days, i'm also having some pain when i urinate?

See your doctor!: Your severe diarrhea concerns me given that you had a recent appendectomy. This could be a sign of a complication such as a partially obstructed bowel. Even if you hadn't had a recent appendectomy, I'd be concerned about the pain with urination. So, my advice to you is two-fold: (1) See your doctor! and (2) See your doctor! I hope all is well, but its best to be sure.