Thanks for writing to us.
The description points more towards a mite infestation scabies
than any dermatitis
Scabies is characterised by itchy red bumps over finger web spaces, wrist, axilla, chest , around navel, groin, genitals and inner Side of thighs. The lesions itch more in night and other family members may also complaint of similar problem.
Treatment requires one time application of permethrin cream
Hope that helps. Take care