He just may be getting sick. However, if he is still doing the same in a few days i would take him to the vet to get him checked out. The poop and puke thing will pass, my seventeen year old cat used to do that from time to time, he ate his food too fast and would get sick afterwards. As for the saliva I don't know what that could mean other than he could possibly have something stuck in his mouth or have a tooth absess that needs to be taken care of. If its the tooth thing the vet can give you an antibiotic for that. If he has something stuck in his mouth, when he is laying or sitting down see if he will let you look inside his mouth. That way you can see if there is something that is causing him to drool, and then you can try to remove it. If you can't remove whatever it is [if there is something in his mouth] don't worry! Often times cats can get these things out themselves.