For years I have bumps that will randomly appear mainly on my upper back of my arms and on my thighs and legs. The bumps are red and only itch when irratated. They last a few days then disappear.
The bumps seem to worsen only when I am on a cruise the bumps then are 10x worse with the amount of bumps, rednes and itchiness. The bumps also will appear on my buttock while cruising. I have never gotten them on my buttock or that bad at home. What are these kind of bumps and what could be causeing them?