What Causes Blisters On Hands With Bruise?

MY HUSBAND HAS BEEN GETTING BLISTERS ON THE TOPS OF HIS HANDS FOR ABOUT 3 YEARS NOW AND NO ONE SEEMS TO KNOW HOW TO TREAT THEM. THEY WILL POP SOMETIMES AND OTHERS JUST GO DOWN ON THEIR OWN BUT THEY LEAVE A PURPLE LOOKING BRUISE WHERE THEY WERE AT. HE WAS PLAYING WITH A PUP OF OURS AND ONE OF HER TEETH BROKE THE SKIN AND HE HAS HAD THESE EVER SINCE. THEY ARE GETTING WORSE.