rash on hands

I have developed a rash that looks like small pimple-like bumps on the palms of my hands (they dont show up anywhere else, just my palms). They are not itchy and disappear on there own after a couple of days. The bumps are recurring though and only break out after i drink alcohol (not everytime i drink alcohol though). I also seem to get post nasal drip and a mild cold at the same time. The very first time they broke out was after the first night of my spring break trip to Key West. Before that trip i had never had a problem after drinking alcohol, but ever since then i might break out with these tiny bumps and/or have cold symptoms. I didnt have any physical contact with anyone, though i did share the same cups as some of my friends. I have seen a couple of doctors, one said they were folliculitis the other wasnt sure and prescribed me a sort of cortizone cream which works but doesnt stop them from coming back. Any ideas?