Hello,
This can be due to irritation of the hair follicles and clogging of pores due to increased sweating in the sun. It can also be due to clogged pores after applying heavy creams and cosmetics and going out in the sun.
Before going out in the sun apply a non greasy sunscreen with spf 30 atleast half an hour before stepping out. Also wash your face with fresh water and reply the sunscreen at frequent intervals. It is important to maintain hygiene and avoid any sweating of the area.
If the white bumps appear, apply some topical antimicrobials like Bactroban or Mupirocin.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
just consult a skin spltst... nothing to worry...