I have IBS with diarrhea and was told by my doctor that medications were a last resort because the side effects were awful. I didn't ask further and figured I would explore it more if I needed them. I would definitely ask your doctor for more information.
The first step he had me take was to add a lot of fiber to my diet. This is very counterintuitive (I figured I'd be living in my bathroom with MORE fiber!), but it worked wonders. I use a no-taste fiber supplement in my water, eat Fiber One cereal and eat foods that have lots of fiber. For whatever reason, it really helps stabilize things. Within a week, I had no diarrhea problems and could leave the house without charting potential bathrooms along my route.
I have since added in Greek yogurt into my diet, which is rich in probiotics. Between the two, my IBS has been a lot better. I still have problems if I eat irritants like chocolate or tomatoes, but just arm myself with Immodium when I splurge.
Good luck! Hope you're able to find a good solution to your IBS.