Unfortunately I dont think there is much I, or anyone else can tell you that will help. You need tests done to rule out things like crohns, colitis, celiac, etc.
If the diarrhea has been the last 2 weeks, its possible that its a stomach bug or food poisoning, though the longest those usually run is 10 days.
Try eating a bland diet and see if that helps. Grilled Chicken, light fish (flounder, talapia), rice, and steamed veggies.