Stressed Male Rat?

Question
QUESTION: Hello. Recently purchased 3 little male rats, about 6 weeks old i think, and although 2 seem fine and dandy, the 3rd one seems almost sad and withdrawn. He spends the entire day in his box and although is still drinking, he has shown little interest in food, only grazing from time to time. They were from a petstore unfortunately so probably have never been touched, but the other 2 seem fine. Does this sound like a stressed rat? Maybe a sick rat? Will be seeing a vet next week but is there anything i can do in the meantime? thanks for your help

ANSWER: How long have you had them?  I would try to get him to lick some baby food from your finger. He needs to keep nourished as much as you can.
Is he sneezing at all?
Also, if they are shy, here is a good way to get them to learn to trust you:

http://www.freewebs.com/crittercity/trainingshyorbitingrats.htm

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QUESTION: Just on a week. He doesnt seem scared when handled or anything, he even licks our fingers, its just when he is in the cage, straight to bed he goes lol. Yes all 3 sneeze which is why they will be visiting the vet next week. Is it possible that he's just a sleepy lazy rat? Or maybe not coping with the myco as well as the other 2? Thanks again for your help

Answer
Sneezing is pretty common for new rats. they have alot to adjust to in their new home, new smells, etc...  but if he seems lethargic, it could be a secondary infection. I hope not. They are awfully young to even have mycoplasmosis. Usually myco takes a long time to start showing signs, not at this young of an age.  

What type of litter/bedding are you using?