Poor you, sounds like you're really suffering. Ibs isn't just a tick box of symptons which is why it takes many doctors a long time to pin point it and some too quickly.
I can't comment on your medicine, I have no idea. I'd take an acidophilus supplement to return the good bacteria to your gut.
Try following an ibs diet, their's some suggested on this forum, you may pick up some ideas of what triggered it and avoid processed foods, they make all ibs suffers life hell.
Hope this helps, you have my sympathy