The positive thing is that you see him drink occasionally. I never saw my snake drink until I put him into a bath 3 weeks after I got him. So if you see him drink on more than one occasion in one day, he's definitely hydrating himself. When he was at petco or whatever pet store you got him from, did he happen to be in a tank with other snakes? If so, he's already infinitely happier because you really shouldn't keep multiple snakes in the same enclosure. When you feed him, put the mouse in a plastic bag and thaw it out with warm water for like 10 ish minutes. Make sure the mouse is thawed all the way and is warm so that it mimics the temps of a live mouse. If dangling it by it's tail doesn't work, use tongs (I use plastic chop sticks that have the spring in between them) to dangle it by the scruff of it's neck. The snake can find the head easier sometimes that way and it makes it easier. Something else to try is to just put the mouse on a piece of newspaper and let it be over night. If the snake doesn't eat it by the morning, scrap it and wait 5 days. I had problems with my guy eating and he didn't eat from October 28th until November 13th.