Which docs are telling you to use OTC drugs to treat your allergies? Endocrinologists? General practice docs? I'd suggest going to see an allergist/immunologist and having them run the whole battery of allergy tests, to see what exactly you are allergic to.
I had this test done back when I was a kid, in the early 1980s. It entailed laying down on a bed and them doing slight skin scrapes, followed by putting a solution on the scraped surface which contained whatever one might be allergic to. Whichever ones I reacted to (lots of pollens, danders, etc.) were the guilty parties. It was crystal-clear which things I was allergic too, because the skin would break out and itch like made. So they devised a serum for me, and then I got put on once-a-month allergy shots. The shots totally cleared up my allergy problems.
Go see an allergist.
Cheers and good luck,