Hi Dear, Welcome to HCM. Understanding your concern. As you mention in your query that you are suffering from yellow spots on your jaw line .Basically they are acne that are formed due to mechanical stress on your jaw line like strap of a helmet or mechanical irritation due to some dental appliances .The mechanical injury make skin dead where bacteria accumulate and clog the pores of skin to cause acne. I would suggest you to remove the factor causing mechanical injury ,Consult dentist if it is due to some dental appliance ,apply moisturizer cream ,exercises used for reducing double chin are also helpfuland wash affected area gently twice daily. If condition persists or reoccur consult dermatologist ,who can diagnose it properly and treat it accordingly. Hope your concern has been resolved. Get well Soon. Best Wishes, Dr. Harry Maheshwari