skin diseases

Shelly my husband has something on his hands. Its like hard skin that keeps having sores come out of his skin. Kinkof like bubbles that pop and hurt. His skin seems to be real dry. His one thumb is where the bubbles keep coming from but the tops of his hands are real dry and red. We went to the dermatologist a couple months ago when it was only on his thumb and she wasn't sure what it was so she gave him a Antibiotic in case it was an infection and also a cream. that hasn't helped. Now we thing he is getting it on his foot. He asked me what was on it cause it hurt and it looked like his thumb. Do you have any idea?