Hi there,
I am exactly experiencing same problem, I was diagnosed for IBS and I also have severe itching rush ,I involve with this about 7 month and still struggle....., I`ve just started to take Gluten free diet, but I do not know if it is working or not
Hives are probably from allergy - may be food, medicines, soap, clothes...To test, if it is an allergy, you can try an antihistamine pill Benadryl - itching should stop shortly after that.
To find out, if it is some food that causes allergy, you can ask a dietitian to give you a diet plan, starting with complete fasting. If it is food, itching should go away in few days...