It does not matter. Sleep on the side that is most comfortable for you.
Waking up with ear pain similar to an ear infection, when sleeping on that side. It goes away after sleeping on other side. Why?
Could be TMJ? See your doctor. This could be an ear issue, or more likely, perhaps a joint issue at the temporomandibular joint (TMJ) which is right in front of the year. This joint can hurt at nighttime for several reasons including teeth grinding, clenching, or occlusion issues.
Ear pain and pain under jaw pain even in back neck all left side. Dr said no ear infection just red. But I can't even sleep it hurts so bad?
Red? What does he/she mean "red"? No diagnosis? Might be a TMJ disorder. I'd have an oral surgeon look at you. If TMJ, see a TMJ expert. Any dentist can be a TMJ expert with the proper training and experience. Most commonly, oral surgeons, prosthodontists, and orofacial pain specialists. Ask your MD, your dentist and your dental society for referrals.
TMJ. See a dentist or TMJ specialist for examination, diagnosis and treatment. Very common.