What clinic should I go to for a concussion consultation in Tokyo?

Any English-speaking recs for a foreigner with minimal Japanese skills? I hit my head pretty bad recently but feel fine, just want to make sure things are on the up and up, nothing too crazy. Dunno if I should go for an internal medicine clinic or a neurologist, or call the ambulance and have them help me? Would prefer if there were around Shinjuku/Shibuya area for the former.

Thanks in advance!