If the spots look like tiny mosquito bites, then it's probably just an extremely mild form of hives. In my family, all of the girls get these after a shower, but they should go away in about half an hour. If they're gone now, I don't think it's anything to worry about.
Hi, welcome to the forum, her history is suggestive of atopic dermatitis or allergy to water or its contents. Very less has been known about water allergy and it is termed as Aquagenic urticaria. It can be due to exposure to allergens present in water in your area or due to ions in non-distilled water.
If she is allergic to water following measures will help you-
- Stay away from water as long as possible.
- Avoid going in rain outside.
- Keep yourself cool during summer as even sweating will cause reaction.
- Try boiling water before bath and as well can try hot water bath. Avoid showers.
- Dry yourself immediately as soon you finish your bath.
For hypersensitivity reactions oral antihistamines and topical corticosteroids can be taken against prescription. I suggest her to consult allergy specialist.
I hope this will help you. Take care and regards.