Shortly after I made Salem come in side for being outside for about 1 and 1/2 hours, Salem and Rocko were chasing and jumping on each other like they usually do but I noticed the hissing and growling from Salem so I went to check what it was. Salem was viciously attacking Rocko so I broke up the fight and let him cool down and about 10 minutes later when I picked Salem up he tried to attack me which he never does. For about an hour after he was acting so strange, like he would be licking himself all over and twitching, very fast movements and growling at nothing. He was also panting frantically and would not stop. So, we decided not to risk anything and took him to the vet. She checked everything and said there was nothing wrong and he seemed a lot more calm. When we took him back home he was hiding under everything and even tried to go back into his carrier. We've tried to pick him up but he just growls and has been staying in the same spot since we took him home. Anyone have any ideas of what's wrong with him or what happened? [We have the idea that something could have really freaked him out while he was outside. He doesn't have any bites or scratches on him that we can see.]