blood blister breaks open and bleeds, sensitive for 3 yrs?

Hi,
Welcome to the ehealthforum and I am glad to help you out.

Blood blister is commonly found on the hands but it is very less common for this blood blister to persist for so long. Elevate the hand,give rest to the part,apply cold compresses,soak the blister in Epsom salt and keep the hand bandaged so as to avoid its rupture. If the blister breaks, quickly rinse the area and apply an antiseptic such as neosporin. It is not recommended to break a blister because it may often lead to infection.

If the symptoms worsen or persist then get it evaluated from a dermatologist.

It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care.