How to help a sick rat?

5 days ago i got 2 baby pet rats, today however one of them is sick, He is not moving much at all and was colder than normal, He is very very sluggish and seems to just be sleeping, Their water and food has gone down, quite a bit, but as there is two of them in there I'm not a hundred per cent sure if he is eating and drinking, Up until this morning he was very lively and running around and playing fine. I have looked some things up and know i need to keep him warm, i have put a t shirt in with him and snuggled him up in it, i have also put in some fresh carrots and made sure there water is fresh. I can't get him to the vets myself and as my boyfriend works we wont be able to get him to one till Saturday morning. Is there anything i can do to help get him better??