Are you sure the odor is coming from BEHIND your ears? If you have pierced ears, and you don't regularly wear earrings, the holes sometimes can fill with sebum and dirt that will have a foul odor....Cleaning with rubbing alcohol or hydrogen peroxide will get all the junk out.
I had something similar for a while. Washing the area frequently with coal tar extract shampoo (Neutrogena T-Gel) seemed to help. It went away eventually.
Hi
Welcome to the MedHelp forum!
Fowl odor behind the ear could be due to sweat dermatitis. Keep the area dry if you sweat a lot. Clean regularly with soap. Wear an astringent there by dabbing with cotton. If there is an infection, then get this treated by applying local antibiotic cream.
It is difficult to comment beyond this at this stage. Do consult your doctor.
Hope this helps. Please let me know if there is any thing else and do keep me posted. Take care!