@proserpine
You've had an awful time of it too for sure. Have you tried icing your side? I get stabbing rib pains (not cardiac - I got all wired up and tested and my heart is surprisingly perfect) and the ice helps until an NSAID kicks in, usually ibuprofen (I think it's called paracametol elsewhere). The trick is to use a thin ice pack so that it lasts just long enough to make it nice and numb, but melts before it can cause any damage.

From what I remember about neurology, I think antidepressants can screw up the nerves in the gut so normal feedback to the brain becomes conscious pain. That or all the physical anxiety/anger isn't helping. Maybe also try mint and fresh ginger tisane. I find the combination to help a lot with stomach problems.

Or a bath with Epsom salts. I do a warm towel on the back of my neck to help with the weird neck twisting that is probably withdrawal. Occasionally I'll get a feeling of tension in my neck and then my head twists sharply to one side. Not painful but annoying and I really hope that no one sees.