Hi welcome to the ehealth forum and I am glad to help you.
You have described lumps behind both of your ears for 4 months and the pain in them has started 3 days ago along with fever with myalgias(pain in neck and shoulders). You also complain of a dry and flaky scalp for a few months and also report no loss in weight. You also have a history of insertion of tubes in both ears in 1989 and other surgeries.
If you are having a dry and flaky scalp suggestive of seborrheic dermatitis of the scalp then the postauricular lymph nodes can get enlarged and remain so for long periods until dermatitis persists, which is usually a chronic condition. The acute symptoms in the form of fever and pain in the nodes and myalgias may be suggestive of acute infection, usually viral, due to stretching of the lymph node capsule as seen in adenovirus and parvovirus infections.
As you have a history of grommet tube insertion in your ears at the age of about 3 years suggestive of chronic middle ear pathology and sequelae, you might like to consult an ENT specialist to rule out any middle ear pathology like mastoiditis, etc, which may have caused the symptoms in your case which started 3 days ago in form of fever and pain behind the ears. The pain of mastoiditis overlies the mastoid bones behind the ears and is quite severe as you are describing in your case. No loss of weight and other features show little likelihood of any cancerous pathology in your case.
But as a definitive diagnosis cannot be offered online, you must consult an ENT specialist for a thorough examination and treatment and a dermatologist for advice on seborrheic dermatitis.
Hope this helps. Take care.