Day after nose surgery noticed 2cm pink hive on back.2 weeks later body covered in smaller pink hives and the big one now looks bruised.circle flaking?

Hives: Were you given an antibiotic? It is possible you had a reaction. You should consult with your surgeon.

Get eval: Rashes are almost impossible to diagnose over the computer. Could be allergic reaction or a fungal infection, etc. Get an evaluation and visible inspection of the rash by a Health care provider and then the proper treatment would follow. Best wishes.