Hi Jeremy,
A swollen abdomen can be minor due to intestinal parasites, or it can be serious due to a stomach twist, heart disease, cancer etc. I am recommending you return to your veterinarian and request some diagnostics such as a series of blood work and lab tests,, and a couple of abdominal xrays.
Jeremey....I have an idea: Google IVDD (Intervertebral Disk/Disc Disease) More than likely, that's what your dealing with.....Doxies are the #1 Breed to experience this......
Also, your dog should not be walking, running or playing.......Crate rest is a must for 4-6 weeks to allow for the disk to heal.....From your description, it sounds as if it's getting worse......If it ruptures, then you could be looking at Paralysis & emergency surgery is recommended....
With the correct medications & cage rest, you can get him over this.....You must follow instructions to a tee......Carry him out to potty and carry him back in & put in crate.
I am not the Vet, but thought you needed a response soon......You can also post your question in the Dog Forum.......Good luck