What Causes Hives In The Knee And Groin Area?

I had a Laproscopic cholecystectomy 3 weeks back, a week after the surgery I developed hives on both sides of my groin area and inside the knee. a week later on either side of my abdomen and it continues, I have been googling this and read that it could be an allergic reaction to the dissolvable stitches, is that correct?