My guinea pig Spunk has been sick for a little while now. At first I noticed his poops were very small and dry, and then he started sleeping all day. I took him to a vet who misdiagnosed him with an uri. I then took him to another vet (who I love and trust with Spunk but was booked before) and he did many different tests. He thinks Spunk hurt his neck and is in a lot of pain. He prescribed him medicine for his pain, told me to keep him on the antibiotics just in case, and gave us critical care. Now he is very energetic and mostly back to himself, but he now has diarrhea. Any advice?