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 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 had these signs?
Where is he retaining fluids (ie his abdomen, chest, under his skin, etc)?
Did you vet sample/test these fluids to determine what they are and their cause?
Any history of other health issues?
How is he otherwise? Feverish, unwell, breathing changes, or anything else?