My male rat, Siegfried, is experiencing respiratory problems. We thought he was choking two nights ago, as he was opening and closing his mouth and running around frantically trying to escape his cage, but he seemingly recovered and was ok. However, about half an hour ago he started doing it again and hasn't stopped being distressed since. He is sitting still but isn't himself. There is no frothing around his mouth.
He is a year and a half old albino fancy rat. He has lost quite a bit of weight lately, which may or may not be related to this issue. He eats and drinks normally. He had an infected sebacious gland a few months ago but that is healed now. He lives with another male rat of the same age.
Thanks for your help.