My 7 Year Old Golden Has Developed Golf Ball Sized

My 7 year old golden has developed golf ball sized lumps under his chin. Had biopsy done and came back negative for cancer. Vet thought it might be a reaction to something and suggested i put olive oil on his food. It has been a month and no change. He eats fine but drools now. never did before. also snores and makes weird noises when sleeping. never did before. does not seem in pain when i feel them but he does seem sad to me