Ok, that is good that he has had his first vaccines. And I DON'T think this is Parvo as he sounds too bouncy and playful for that. I'll come back to this - scroll down!
As you probably know, he would now be due for his next vaccines.
Normally we vaccinate pups every 3 to 4 weeks until they have had 3 sets of "DA2P" vaccine, followed by a Rabies vaccine at 20 weeks (the age for the rabies vaccine varies by law by state/province, and is sometimes as low as 12 weeks or as high as 20weeks).
This DA2P vaccine covers the pup for:
1. Distemper virus - this deadly virus is very rare now, thanks to routine vaccination. There is very little effective treatment if a dog gets Distemper, and most dogs die or have lifelong health problems if they survive.
2. Adenovirus Type 2 - this is a virus that can cause Hepatitis in dogs. This is potentially fatal, but also rare due to vaccinations.
3. Parvo virus - this is a virus that causes vomiting and diarrhea in dogs, often resulting in death, particularly in puppies. It is more common than Distemper and Adenovirus combined. I unfortunately see plenty of cases of Parvo in dogs that are unvaccinated.
And, finally, the Rabies vaccine is given when the pup is old enough. It is a LAW in most countries that dogs must be vaccinated for rabies.
Here is more about vaccination of puppies:
Now, in terms of what is going on with your pup causing the soft stool with blood and the one time vomiting, there are a number of different things that could cause it, but these are the ones that come to mind first:
1. MOST LIKELY cause would be Parasites.
Some internal parasites (worms) are very difficult to detect on a fecal analysis.
So, even though the fecal might be "negative" the pup could still have worms.
Here is a link to information about whipworms which are notoriously hard to identify by fecal analysis, and are not killed with pyrantel pamoate (standard puppy dewormer):
Blood in the stool of a puppy is very often caused be COCCIDIA which is a type of parasite (not a worm). Coccidia is a protozoal organism, quite similar to what causes Traveler's Diarrhea in humans.
Coccidia is what I feel is most likely in your pup!
It can be treated with a course of S-125/Albon medication.
Here is more about this problem:
2. Dietary indiscretion:
With a pup, one always has to consider dietary indiscretion (garbage gut) since they are so curious they will eat just about anything. So, he might have eaten some leaves out in the yard, or a spider, or just about anything.
3. Viral infection:
Since your pup has not completed the full vaccine series yet then he is not fully protected from Parvo virus.
It is faintly possible that Ace could be in the early stages of this, though it is unlikely. Another virus that causes diarrhea in pups is Corona virus. For both of these viruses, treatment is supportive - meaning that it is aimed at maintaining hydration and preventing bacterial infections. Most dogs require hospitalization at a veterinary hospital.
4. A bacterial infection: Dogs can be affected by overgrowths of bacteria in the intestines. In an adult dog these might not be more than a nuisance, but in a pup they can be serious. The 3 most common are Campylobacter, Salmonella and E.Coli. Here is a link with more information:
In summary, there are a number of different problems that could be causing Ace to have blood in the stool.
The top of my list would be Coccidia. The standard roundworm dewormer will not treat this. Some of these problems are very easy to cure, and some more difficult. I would strongly recommend you take Ace in to see a veterinarian in the next couplee of days, and take along a fresh stool sample.
If this has been helpful, please hit the green "Accept" button. I will still be here to answer further questions, just hit reply.
The above is given for information only. Although I am a licensed veterinarian, I cannot legally prescribe medicines or diagnose your pet's condition without performing a physical exam. If you have concerns about your pet I would strongly advise contacting your regular veterinarian.
Best wishes to you and to Ace!