Please help.

[Mr.Harrison]

My snake is around 3-4 years old, it's recently stopped feeding. I've just woken up at 2am to notice my snake upside down in its cage eating it's self. I've now got it out the cage and it's acting very strange. It cannot keep its self up. Keeps biting random things, squeaking (not hissing) it also keeps rolling over and opening its mouth . I've tried feeding. Checked temperature. Cage was recently cleaned etc...