I have 3 or 4 lumps on my left scrotum under the skin. feels heavy and painful when lightly pressed. what could they be?

Scrotal lumps: Most likely the epididimis; a coiled structure that comes from the testicle. Could be varicocoele or hydrocoele or sebaceous cysts. Testicular cancer is different since it's a mass right in or on the testicle itself.

Get checked to know.: These lesions would likely need to be examined and more history obtained to be able to provide you with useful input about the diagnosis or possible treatment.