Sorry to hear that Henry!
Like the guys have already said - speak to a specialist rather than just your GP and do some research / experimentation as to diet - it's easy to be sceptical but it can make a huge difference for some folk.
Personally - I find caffein and tomatoes are big irritants.
There is a lot of diet related info out there - but you have to figure out for yourself what works for you - it is worth looking at though because it can make as big a difference as the meds.
Take care
OH