Both my boys are about 6-7 months old, are living together and came from the same litter. Two nights ago after coming home from work (at around 1am) one of my rats, Obi, was extremely skittish and nervous. He didn’t come up to the cage as usual and just stayed hidden behind his exercise wheel. He was uninterested in coming out to play and taking treats (until I offered some cheese and he took it, but reluctantly) His brother Loki seems completely fine as per usual. At first I thought maybe he smelt something that freaked him out, but this has been going on for 2 days now. He’s eating, drinking and grooming fine and occasionally plays with his brother. I can just tell that there is something off with him though, he doesn’t want to be picked up much or even stroked often. He seemed alright-ish in the daytime today, but the odd actions emerged again now in the evening. Any ideas? I gave him a body check to make sure no lumps popped up, his breathing is good, no extra porphyrin than usual and in general he looks healthy minus his behaviour changes.