welcome in H.C.M.
I have gone through your query regarding pain on your left side of ear ,back on mastoid and reaching down to shoulder, your E.N.T.doctor says ear is ok .You got some better feeling after antibiotics.
After considering all aspects of your complaints I would like to say that am agree with your E.N.T.doctor's opinion because -
(1) Area involve in pain can't be explain by ear pathology.
(2) You have no complaint for loss of hearing and dizziness
. Because deeper ear pathology is usually associated with these symptoms.
So most probably you are having dental pathology and referred pain
in left ear. You have also said about some dental work in long back.
I think your query is now explained well.