One of my rats has been acting particularly worrisome lately. He seems to spend the majority of his time hiding, only coming out to eat and drink occasionally. He also seems to have trouble climbing up to higher places in the cage, which has never been an issue for him before. It's worth noting that he recently had an abcess burst, and there is a scab on his neck where it was. But I don't know if that actually has anything to do with it, or if the issue is something completely unrelated.