Hi, my 21-year old desert tortoise recently woke up from hibernation. I've taken out and put it in a cozy room with heat and lighting, as well as allowing him to drink, which he did during his 1st few days out of hibernation. Soon after, I took him outside and let him loose in the backyard to eat and whatnot. He was very active and walking around the yard, hydrated and happy. Just yesterday though, he was burrowing near his habitat and today, he hasn't moved since the burrowing. I'm really nervous and don't know what to do now. The temps outside are high 70s during the day with sunlight, but at night, it's about high 40s. What should I do now?