What Is The Treatment For A Purple Color Pimple Under The Eyelid?

Hi few months back i developed red/purple growth almost like a pimple on upper eyelid (not next to eyelash so i ruled our stye or chalazion) which has been slowly getting bigger with smaller growth developing next to it. About 6 years ago i had malignant melanoma on top of tigh so new growths can b scary for me. Please advise other things this may be or if i should seek urgent medical advice from my own gp.