We had a 6 month lepoard tortoise who lives inside and doesn't hibernate. He was doing exactly the same thing and so we got him a little girlfriend and he is so much ahppier..he eats more now, runs around,and loves his baths!
If you dont know his sex for definate already then i would take hm to an experienced breeder and get it checked and then speak to them about suitable partners...he will be unhappy if his partner and him dont get on.
Hope this helps
leanne x