Hello & welcome, I am Dr. B, a licensed veterinarian and I would like to help you today. I do apologize that your question was not answered before. Different experts come online at various times; I just came online, read about your wee one’s situation, and wanted to help.
Again I do apologize that my colleagues could not aid you sooner. If you would still like assistance, can you tell me:
How long has he been showing signs?
What does the diarrhea look like? Any blood?
Does he sound hoarse, have any gagging or issues keeping water/food down?
Are his gums nice and pink (not white/pale)? Moist or sticky?
If you press on his belly, any tensing, tenderness, discomfort, or pain?
Could he have eaten anything he should not have (ie bones, toys, plants, chemicals, human meds, etc)?