The most likely cause of a lump behind your ear is a lymph node. Lymph nodes are present on both sides of the ear, and they are involved in helping your body fight off infections. Sometimes after a recent infection, a lymph node may stay enlarged for several weeks before starting to decrease in size. I would definitely keep an eye on this lump. If it continue to grow or persists for more than 4-6 weeks, you should go see your primary care doctor
to have it checked out.
with lymph nodes is that when they are persistently enlarged this can sometimes be a sign of a serious evolving medical problem, such as a lymphoma
. Your doctor will be able to examine the area of swelling and determine whether additional workup is needed, such as a biopsy of the lymph node. When you go to see your doctor, make sure to mention if you have noticed any swollen glands elsewhere in the body or whether you have been having other concerning symptoms such as recent loss of weight or night sweats.
If on the other hand the lump starts to go away, you shouldn't need to worry!