Dog Panting Hard And Fast Back Legs Swollen 11 Years Old Lab Vomiting And Diareah Legs Swollen To The Max Can Walk Still And Eats And Drinks But Is Not As Active Can Not Run And Has Trouble Getting Up, What's The Matter?

The panting is secondary to pain, stress, or discomfort most likely. Diarrhea is common in dogs and can be caused by many things. The gastrointestinal tract is the stress organ in dogs--the problem may be primary a gastrointestinal issue or may be secondary to other disease. Common causes of diarrhea in dogs include dietary indiscretion, intestinal parasites, Giardia, pancreatitis, foreign body obstruction (usually with vomiting), infectious diseases (parvo virus in an unvaccinated puppy or young adult dog), stress, metabolic diseases, and bacterial overgrowth. As your dog is experiencing other symptoms I would seek veterinary medical attention.
Most uncomplicated (no other signs) diarrhea resolves in 1-2 days. Veterinary medical attention is needed if the diarrhea lasts longer than 2 days or further signs develop.
At home you can try feeding a bland diet--boiled chicken, boiled rice, canned pumpkin, and canned yogurt.

My dogs lower back and thighs have swollen spots on them.

My dogs lower back and thighs have these swollen areas on them.

Sometimes you can get a lower payment by going to a shelter and seeing their vet or try a different vet that might offer a payment plan--this dog is very sick and needs to be treated.