If the whole inside of the container was wet or showed visible condensation then there is not proper ventilation. Its either the water (if any is provided) or the mouse's own urine trying to evaporate. Its a good combination for causing a cold and or respiratory issues.

If he was weaned to early and can't sustain on solid foods the shaking could be the result of the body breaking down. If you don't see it eating or drinking than its quite possible its going through a slow painful death. You could freeze it for later use before its completely wasted and dies due to lack of nutrients.

I also don't agree with your comments about not being truthful with your guardian/home owner. There are enough bad examples of people with animals, don't be the start of one those stories. But I guess that's not really my business. Good luck with the mouse!