Hello,
These skin bumps can be sweat dermatitis,contact dermatitis or heat rash. Avoid using any lotions and creams for the meantime.Use a mild cleanser with moisturizing properties like Cetaphil. Also use cotton clothes and change the clothes twice if there is any increased sweating.Try keeping the skin free of sweat as far as possible. If the symptoms still persist then you can apply mild steroid like dermacort.For the itching antihistaminics like Benadryl or Claritin can be taken.
If the symptoms persist then it will be best to consult a dermatologist.
Hope it helps.Take care and pls do keep me posted on how you are doing or if you have any additional queries.Kind regards.
Look like pityriasis rosea,it is self limiting and rare to recur.
also they just appeared 2 weeks ago after swimming very slight sunburn, they kinda went away but i dont want them to flare up again whatever they are