Thanks for writing in.
The most common cause in your case is pompholyx
It is caused by a type of endogenous eczema.
It is common and treatable.
You can take oral medications like antihistaminics and steroids
Also you can apply steroid antibiotic based cream over the affected area.
Keep the area clean and dry.
It better to visit a dermatologist
before taking these medication.
The rash is considered noncontagious.
I encourage you to visit a qualified dermatologist for proper advise and treatment.
Hope this helps.
STD & leprosy