Zithromax and High Liver Enzymes

Just found out liver enzymes were 500 and 300 last week, doctor did liver ultrasound and every liver blood test imaginable and all were ok. After a couple of days, enzymes came down to just about normal.  Feel fine. On June 1 enzymes were normal - the only thing different between now and then was that I took a 5-day Z-Pak for sinus. I also used ibruprofen (2 - 4 a day) for a couple of weeks, but I have used an occasional ibruprofen for years. Dr. thinks must have been build up of ibruprofen with the Z-pak. Has anyone else heard of this before?  Thanks -