What Is The Treatment For Itchy Palm?

for the past year i off and on i have been getting itcy palm on right hand. Once it starts itching i know a bump will come. I can feel them under the skiin coming more as i scratch. Now it is at the bottom of my palm were it meets my wrist. it is painful and does not itch anymore. it looks like a blood blister but nothing comes out when i try to pop it. can you tell me what this could be.