2 Weeks Ago I Had A Stent Put In My

2 weeks ago I had a stent put in my right groin. I have been feeling much better until yesterday. Suddenly my stomach starting hurting me around the tight side of my belly button. Upon feeling around I have felt several harden areas under my skin. Also around the area of where I was cut on my groin has a harden area about an inch or so. Both areas are almost black in color. A couple of the knots in my stomach are some what more painful as the night progresses. It seems like something like this always hits me at night and or on the weekends. Got to admit I'm not in as much pain as when I had the actual heart attack but I am concerned. Should I be?