I Had Tissue Removed After A Mole Came Back Moderate.

I had tissue removed after a mole came back moderate. They used dissolving interior stitches. After almost two weeks I broke out in hives all over my body that itch like crazy, my arthritis in my knees is inflamed. How long will this last. Went back to dermatologist last Tuesday he removed exterior stitches looked at my rash and said caused by interior stitches which are almost three weeks old now. He gave me a steroid shot and said take Benadryl how long can this last it is miserable?