A rabbit that has true diarrhea and refuses to eat needs to see a vet.
How old is your rabbit? If she’s a very young bunny she needs to see avet right away, because true diarrhea in young buns is more often than not fatal if left untreated. Young bunnies get dehydrated quickly. They also get hypothermic, so keep her warm in a blanket until you can get to the vet. Feel her ears – outer ear temp is not the best way to determine a bun’s core temp (for that you need a rectal thermometer), but if they’re ice cold or burning hot it gives you a clue.
As for the diarrhea: Is there any round poop together with the diarrhea? Is there mucus in the diarrhea and is it very runny and profuse?
Please get back to us with more info.
I very much doubt the small piece of newspaper is the cause of this. Bunnies often eat a bit of paper or cardboard, it shouldn’t cause diarrhea. If a bun eats too much of it it can cause constipation though.