Where to go on general health problem and not specific problems?

Hey guys, wanted to ask if you don't know what's going on with your body and feeling generally unwell which hospital do you even go in Japan? When I look up hospital it's divided to neurology or oncology etc but what happens if well multitude of it hurts? Do I choose 内科?? Can't really figure out the health system of Japan and feeling unwell.
Thanks in advance