I purchased a Ball Python from a local pet store last week. He is incredibly thin and was not taken care of properly before.
Last night I was able to get him to eat a fuzzy mouse, which was amazing since he is so thin and in dire need of food (We were sooooo happy he finally ate).
Today he drank from his water dish for the first time, and I am noticing odd behaviour.
He has been sticking his head straight up, as if he is trying to keep the water down, for about half an hour now.
He actually just lowered his head, however it looks like the water is still resting just bellow his throat.

I realize that this is a sign on RI, however he isn't exhibiting any other signs of IR... He is not open mouth breathing and there is no clicking or wheezing sound when he breaths. We are trying to get this little guy back to a healthy state!

Is this possibly a sign of stress? Or maybe because yesterday was his first meal in what I assume was months, is he having a hard time keeping things down?

The warm side of the tank hovers around 90 degrees, the cool side is around 75
He has a hide on the cool and warm side, the water is in the middle.
He is is a 20 gallon long tank.
Aspen bedding.

Thank you all in advance!