HELP!!!!! My Guinea Pig has severe diarrhea and is twitching!?

He went to the vet for severe diarrhea and is on medicine for it. We're giving him water since he won't eat and have hay in his temporary hospital cage. He has a blanket and we are also giving him orange juice, (as recommended by the vet,) and mashed banana, (recommended by another vet,) with water. He has suddenly started twitching and seems like he might be trying to stand up. He also made a little noise. Please help, he's lately been doing better, but now I'm scared, help!