Hello,
Since you were having juvenile rheumatoid arthritis, so it can be related to that. The other possibility is of pompholyx. Pompholyx is also called dyshidrotic eczema. It is characterized by a sudden onset of many deep-seated pruritic, clear vesicles which itch and then peel off. As a result the skin may also fissure.
The exact cause is not known and excessive sweating can be one of the reasons. But some triggers like allergic reaction to soaps, detergents, foods, latex, nickel etc may trigger the symptoms. Apply some calamine lotion on the affected area and keep the area well moisturized. Use only thin applications of moisturizer ointments as excessive amounts of ointment may restrict breathing of the skin and aggravate the condition.
Topical steroids can be applied but they are available under prescription. Moreover to prevent infection, topical antibiotics may be needed. I suggest you to consult a dermatologist and get it evaluated.
I hope it helps. Take care and regards.
Does it swell up at all or look like it might have fluid in it? Years ago I had synovitis on my forefinger, inflammation of the synovial membrane, and is often associated with arthritis. The doctor put me on a medication, probably like prednisone, and it went away.