Help with 2 year old ball python

[ZargZ]

Hey guys, long time lurker. first time poster, basically without going into a huge story, about 6 months ago I was in a car accident that almost killed me, well technically it did for a few seconds, but thats beside the point. regardless I was in recovery unable to care for myself for the last 5 and a half months, and unfortunately the care of my ball python "Kaa" fell upon my mother. She tried her best but knows very very little about snakes, so she was feeding him extremely small meals and not maintaining his temperatures. So, Now that I've been able to look at him, he seems considerably weaker than before and I can easily move his skin around while also being squishy and today when I walked in the room and turned the light on suddenly, he started bobbing his head back and forth for a second so I got him out and monitored him but didn't see it again... I've gotten him some small rats and gave him one 3 days ago but I'm not sure how often I should feed him after having little food for so long. Can anyone please help me out with a general rehabilitation plan to get him back on track, if I even can?

I feel terrible and it makes me upset every time I see him like this