Should i go back to er? in a lot of pain from procedure eight days ago. i have eight stints and had another heart cauterization last thursday, eight days ago. i have some swelling above the incision site, minimal, but the pain in my groin is getting worse

If : If you are having continued or worsening pain after a procedure - especially 8 days out, you should be seen by a physician. First, you should call the doctor who performed the procedure for advice. They may prefer to see you themselves during office hours or may direct you to the emergency room. If you are unable to get a hold of them, you should just go to the emergency room. Worsening pain without swelling in the groin after a heart catheterization could be a caused by something serious such as a deep vein thrombosis (a blood clot) in the vein.

Yes: You need a sonogram of the site to ensure that it's nothing more than swelling / bruising. I'd either call your cardiologist to arrange it or go to the er to get it done.