What Causes Temporary Itching And Burning Bumps On Left Hand?

my friend has recently had bumps show up on her left hand only. just the hand not wrist or finger. She said they itch and sometime burn. She has tried Neosporin and cortisone with little relief. they are only on her left hand an no where else. they last for about a week and a half then have return only at her friend s apartment-- yes I know this sounds weird. there are not pets at either place. no changes in laundry soap or other soaps. She said she has scratched to were they have drained but otherwise they don t any suggestions