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 old is your dog and is he up to date on vaccines?
How long has he been showing signs?
How much blood are you seeing (a spoonful, more or less)?
Are his gums nice and pink (not white/pale)? Moist or sticky?
If you press on his belly, does he have any tensing, tenderness, discomfort, or pain?
Could he have eaten anything he should not have (ie bones, toys, plants, chemicals, human meds, etc)? Were the bubbles just made of soap?