Recurring Rash after Surgery

Two weeks post-surgery last December, I developed a rash on both sides of my neck along the muscles behind my ears.  It was a lumpy, red, itchy area about 2 inches wide and 3 inches long.  I thought it might be the beginnings of ringworm, so I used over the counter antifungal creams on it for three months while it came and went.  Every time it came back, it scattered out more toward the front of my neck and itched less.  I finally went to my GP and she diagnosed it as eczema and prescribed a topical corticosteriod,but it didn't phase the rash.  I put up with it for another 3 months before going to a dermatologist who also said it is eczema and needed the same treatment.  What I don't understand about this diagnosis is that my rash is lumpy and never dry or scaly.  Since June, I have also had a recurring sinus infection that gets worse at the same time as the rash.  I was given Bactrim for the sinus infections, which made the rash worse, and predisone for the rash, which made it better.  I can't take these medications forever, so I would like to find the reason for these ailments, especially since they seem to be related.      I would be very grateful for any new insights!  Thank you!