I am always worried about getting melanoma. i wear sunscreen, get yearly (sometimes more) full body checks and do self checks.how can i quit worrying?

Sounds like a phobia: Phobias are unreasonable or irrational fears. They interfere with one's ability to live a happy, normal life. Psychiatric evaluation and treatment is needed. Best to start soon. Sometimes, one's primary care doctor can evaluate and start medication for anxiety or obsessive symptoms, if the patient does not have easy access to a psychiatrist.