Loose bowel movements ociated with diarrhea everyday?

I can't remember when this all started but it was over a year ago. But it was worse in my last year of highschool. I am very shy and nervous alot. I'll get right down to it: i have cramps sometimes and need to go to the bathroom. I usually feel pain when I go, not in my rectum just like in my abdomen. The need to go increases when I get nervous which is basically all of the time when i'm at work or in any store. That sucks cuz i will be in walmart and the pain and pressure starts and I need to go. Im surprised when I actually have one bowel movement that is normal and the rest of the day they aren't. Pepto doesn't help all of the time only occasionally. It really sucks at work cuz i work monday through friday 9am till 430 or 5pm and i try to be in good mood but my stomach won't let me. I just wish I could be regular. Im going to try to eat a serving of yogurt a day for two wks and see what thar does for me. Car trips for me are sucky cuz i get dirreaha. Throughout the day I make about 5-10 trips to the bathroom. I went to the doctor almost a year ago and he put me on lexapro, and that pretty much worked but i can't remember if it worked all of the time. I quit taking it cuz it's not good when you're pregnant and i'm trying to get pregnant. Can someone please help me?