Four year old comes from hospital after knee/leg surgery. We need to go back and he refuses to go anywhere near the car.

My son suffered a really bad knee injury about a month ago now. I live on an army base with my husband, and they provide daycare here if you need it. While he was there he walked towards some rocks, slipped and fell down this hill. He needed surgery on his knee to repair the damages done when he smashed his knee against the rocks.He needs to go back their every week to do his exercises, but it's just he doesn't want to go back. He associates the doctor with having to do painful things. Advice? via /r/Parenting http://ift.tt/2rTSnO8