I am sorry to hear about this concern for Olly.
Well, we have to be careful not to assume the diarrhea is due to the vaccines, although temporary diarrhea can be a reaction.
My primary concerns for diarrhea with or without blood include:
- Dietary indiscretion (eating something you do not know about)
- Stomach or intestinal foreign body
- Something that was given to them (new food, new treat, human food)
- Intestinal parasitism (not just the worms, but the microscopic bugs like Giardia and Coccidia). They can cause vomiting also.
- Toxin exposure would be less likely, unless you have reason to suspect exposure to a chemical.
- Less commonly, endocrine diseases.
If a fecal test has not been done in the past 1 year, that would be a very good idea!
To help diarrhea you can give some pepto-bismol, but I strongly discourage using it repeatedly as it can cover up a more serious problem. Pepto-Bismol or Kaopectate
You can give it every 8 hours. The average dose is 1ml per pound of body weight, and that is the TOTAL dose for the day. So, if a pet weighs 30 pounds, they would get a total of 30ml a day or 10ml every 8 hours. This is dosing for regular strength Pepto-Bismol. If you use maximum strength liquid, give half as much.
Otherwise, 4 days is worth a vet recheck evaluation and they would likely prescribe some medication like flagyl (metronidazole), which would be great.