My new albino ball hasn't eaten for the past six weeks. I know some snakes fast during winter, but he went off food on 01/14 and is kinda small for his age. He was raised on live mice, which I have been trying. I also tried frozen mice, pre-killed mice, and frozen small rats. He was 834g when I got him and I think he was dehydrated because he went up to 852g in water weight before shedding. After shedding, he went down to 847g, then this week he is 841g. He has had two urates since then. So, he isn't losing much. At what amount of loss does it become more than just not wanting to eat?

1. How long have you had your ball python?
Since 01/30/13
2. How old (or how big) is your snake?
2 years old. 842g, 39 inches long. He was raised on mice and is small for his age, but the vet said he wasn't too thin. He came to me at 834g and has fluctuated between 840 and 852.
3. Does it eat on a regular schedule?
I'm not sure of the exact schedule he was on, but his last meal was 01/14/13.
4. How long since its last meal?
6 weeks
5. What type/size prey is being offered?
Live 25-30g mice. I have also tried pre-killing the mice and zombie-dancing them as well as just leaving them overnight. I have tried inside the tank and outside the tank. I have tried the same with frozen mice and frozen small rats as well.
6. How often do you offer food?
Every monday.
7. What type and size of enclosure does it live in?
Exo-terra 36x18x18. Plastic over 3/4 of the mesh. Back wall has the decorative insert covering the glass and the other three sides have been blacked out 6" up.
8. What are you using as substrate? If it has depth, how deep is it?
1/2-3/4" of Eco earth substrate, currently dry.
9. What type of heating do you use?
UTH + 60W CHE
10. Do you use a thermostat to control temperatures?
Hydrofarm on the UTH.
11. What do you use to measure/monitor temperatures?
Exo-terra thermo-hydrometer under hot hide.
Exo-terra thermo-hydrometer under cool hide
Accurite outside hides checking ambients.
12. What are the surface and ambient temperatures in the enclosure?
Hot surface - 88-92F
Cool surface - 78-82F
Ambients - 77-84F
13. What is the average humidity level?
50's-60's. Morning and evening I mist any areas that are at or below 45-50.
14. How many and what type of hides does the snake have?
Two large (just wide enough to fit him coiled) half logs. One has a branch in front that covers all but a ~3" entrance, one covered by silk plants on the front. He uses both and enters them from both the front and back (backs pressed against blacked out walls but sometimes he pushes it forward with his head to enter from the back side).
15. Is water readily available at all times?
Yes. 60oz ceramic crock on cool side)
16. Does the snake live alone or does it share the enclosure with anything else?
Alone.
17. How often and for how long is the snake typically handled?
Just once, mid week. He's not well socialized, but I don't want to stress a non-eating snake either.
18. Does the snake have any medical history (old injuries or illnesses)?
He has a slight scrape on his back, I think he hit a rough spot on a log too hard when he was first brought home, but it's mostly healed after his last shed, last week.
19. Do you have any other reptiles? Have you brought in any new reptiles recently?
I am taking care of my friend's 1600+g normal male ball, but he's healthy and elsewhere in the house.
20. Is there anything specific or unique about your situation that we should be aware of?
His previous owner kept him in a tub and said he wasn't handled much at all. He doesn't strike but hisses a lot. I had originally taken him to the vet for a check up three weeks ago because I thought he may have been wheezing, but it turns out it was just puffing defensively while being held. He does not make noises in his tank other than for two minutes immediately after putting him back in his tank after handling. Two weeks ago, he struck at one mouse, but missed and didn't try again. This was while he was in his hide. Last week I didn't try because he was in shed. He shed most of the way except for his whole face. I soaked him for 30 minutes and it peeled right off in one piece.