We had similar problems, so taught Ben a 'flat' command so he lies on his side.
You can teach it quite quickly with a clicker and once he is ok with doing it, then touch his ears while he is lying flat, and reward, then get him used to having your hand on his ear, then put the drops in!
at first it took two of us so that Ben focused on the person with the clicker who gave the flat command and rewarded, and the other one did the drops, it is all over so quickly they hardly notice
good luck