Hi almost exactly one year ago my sister had a very
large blister come up on her right big toe for no reason. it filled with water and grew larger and larger in just a couple days. Went to doctor and he drained it and cut all of the skin off all around it. From tip of toe to below joint. Last week she had one appear in the same place a little larger ,went to doctor, he did same thing, Although this year she also has had one come up on her left foot over intersection of second and third toes so she showed him and asked if he was going to open it but he didn't said just to watch it and now it is very large too He doesn't know what is causing these would you have any suggestions