My pet rat seems extremely sluggish and tired, when normally more active?

I have four pet rats, two are about a year old now and sisters, and my other two are only a few months old and really close companions. Although I've failed to introduce my two older rats to the young ones due to a terrifying result(the two older ones harshly attack my more timid, submissive rat-the one with the problem) today I stupidly left the four of them in my room to roam while I sat on the floor talking to my boyfriend. I heard loud squeaking and instantly grabbed Sprout(the rat that has the problem), the two older rats were on top of her and I knew it could be bad. Anyway, about four hours later I checked on my two younger rats and I noticed that Sprout seemed extremely sluggish and slow-moving. I scooped her up and gave her some food, she grabbed it like she was starving but when she starting eating it was almost like she was in slow-motion. I tried to get her to drink some water but she refused, I grabbed a eye dropper and gave her some half and half/cream and she lapped it up. I'm very worried that she may have some internal damage or a possible respiratory infection. I do not know what to do seeing as I cannot take her to the vet since it's 11PM at night. If any of you have any clues as to what the problem could be and if I can do anything before a vet visit PLEASE let me know.