Squeaking? Hmmm....like Julian said, he might be going into shed. Also you might want to check for mucus discharge around the nostrils and mouth. If he's clear, he's probably ok. But mucus and wheezing, crackly, breathing means a respiratory infection. I've never heard a snake make squeaking noises though, so I couldn't tell you without seeing him. Check for the RI, check for shed cycle, and make sure the environment in the cage is correct. Good luck!