My Husband Hot His Lower Leg Hit By A Skid,he

My husband hot his lower leg hit by a skid,he went to the doctor and got checked, it was all swollen and purple, but got better, today I looked at it it was all puffy and ref, and look infected,hevwas working on his legs as ll thise 3 weeks,I wanna know now, if it could develop gangrene or so,tomorrow we going tonyhe doctor