Hello & welcome, I am Dr. B, a licensed veterinarian. I do apologize that your question was not answered before now, but different experts do come online at different times. Anyway, I have just come online, read about your situation and wanted to help.
Again I do apologize that my colleagues could not assist you before. If you would still like help, can you tell me
How long has it been since his last bowel movement?
Has he been straining like he needs to go?
Are his gums pink or pale/white? Sticky or moist?
If you press on his belly, does he have any discomfort, tensing or pain?
Could he have eaten anything he should not have (ie plants, toxins, toys, bones, medications, etc)?