Hi,
The short answer is yes there are medications for IBS. But it really depends on each persons IBS as it is a term used when all other diagnosis have been eliminated, in short they don't know. There are such things as fecal transfer, Omeprazole, Acidex and more, Fodmap diets and some even find benefit from probiotics although depending on who you talk to they can be for or against probiotics, even amongst Gastrologists. If it is really bad then prebiotics to help the probiotics to survive while trying to estabilish in the gut.

A word of caution here, with severe IBS it is not advisable to just launch into probiotics as the gut yeast based enzymes can consume it before it has a chance to do it's thing, making the IBS symptoms even worse.

My gastrologist has used everything but fecal transfer and come to the conclusion for me if it feels good, do it. There are foods I'm not supposed to be able to eat which infact I thrive on and yet other foods I'm supposed to be able to eat that react with me. So very much trial and error is how I have come to as very restricted diet that gets me by with less fuss.
I have moved on from mixed to chronic C, unless I over do the laxatives or eat something I know can throw me into D for a few days. It is a constant balancing act to restrict your choice of food but eventually the brain recognises that the pain is not worth breaking the diet for. A constant fight against the see food diet. Everything I see I want to eat!
Cheers