It could be a number of things. There are different types of allergic reactions to a number of things. It could also be exzema which will blister up bumps then dry out and crack. My son has an allergy to Hogsweed and his hands start with itching bumps bad then the bumps go away and large blisters appear and run there course for about a week and a half. We usually give him Benadryl and psorisin ointment and that helps him a lot. You could always try using an over the counter allergy medicine or a type of anti itch cream on your hands.If these things do not help and it persists more than a couple days I would have it checked out by your doctor. Hope this helps you. Best of luck to you. Mellie~