For about 5 or 6 years I have been getting painful bumps on my right thumb (always on the thumb or the base of the thumb, then haven't spread). Sometimes the appear on top such as in the pictures, but most often they are on the underside of the thumb. I used to get 10 - 16 of them at a time, now when I get an outbreak it is usually 5 - 6 of them.
A couple times when this has occurred I get a painful slightly red streak up my arm. I notice that these outbreaks happen if in wear leather gloves, or am in contact with a leather wrapped handle of a tool. Most often there is friction between the leather and the skin (such as digging a hole). After about 4 or 5 days the bumps get large enough to pop with a pin and then I drain the pus and fluid out to release the pressure. From when they first emerge they are usually cleared up in about 14 to 20 days. Then it might for for a month, or 6 to 8 months before I get them again.
Any thoughts of what this could be? Thanks in advance.