I was just catching up with posts i missed and found your post.Welcome to HW.You really have had a nightmare time with your last flare.I have read on here about
heart problems related to heart attacks, but i think you are one of the first UCers her to acually go through it.(I may be wrong)
Did your doctor say your UC is healed fully.If you are still experiencing pain it would suggest something is going on, maybe IBS issues if you are in remission.
Hope you get feeling better soon
keep the faith