My 23 Year Old Daughter Recently Had Breast Reduction Surgery.

My 23 year old daughter recently had breast reduction surgery. 1 week later she had a 24 hour type stomach virus. Now, 4 days later she has developed a fine rash over her upper body. It looks like an allergic rash, but she can not identify any new medication or contacts. Could this her body's response to the virus? (She is recovering very nicely from her surgery and her surgeon is not concerned about the rash).