Hi, you seems to be having allergic rash
from something like your cloth material or dust or soap etc. It could possibly be due to excess sun exposure. You should avoid direct exposure to sunlight for long time. Wear little loose clothes of cotton or stuff that does absorb sweat. you should keep yourself hygienic take regular bath and use good talc powder. You can use lactocalamine lotion on pimples
to reduce them. Avoid scratching them. take a tablet cetrizine
once a day. Wish you good health.