If the dog acts like he's really in pain, it could still be parvo... but the dog won't live long if he has it. If he does, bleach the heck out of your house, walk ways, garage shoes etc.. it's highly contagious. I had a dog of the same age suffer parvo even with shots, luckily he survived but that was after spending a week at the vet with 2 treatments and $2000.00 later.
To help you save money on shots -
TSC has the yearly dog shots in the store for about 5$. Easy to administer - if you want to do yourself PM me, I do all my own dogs (4 mastiffs). I'll walk you through on how to do it, it's really easy!
For internal upsets this is what I do:
for run of the mill diarreha, I'll give them an adult dose of either Pepto (liquid with a syringe or tablets) or Imodium - will clear up in a day.
For really sick:
NO food for 24 hours. (water always available) Activity restricted to crate and leashed walks outside.
The next day I feed 2 to 4 very small meals of cooked white rice, chicken broth and plain yogurt. Don't give him anything else.
watch stools and behavior. You should see some improvement fairly soon.
The rest of the week, I feed cooked white rice, chicken broth, yogurt and cooked hamburger (I use venison - NO fat) or you can add a small amount of their regular food. During this week I start with more rice add more meat/dog food and less of the rice and transition back to regular food.
If the dog is looking at it's side alot, lethargic, drooling and hanging it's head, it could have a blockage in the stomach. You will have to have surgery or the dog will die. Sometimes the barium test they give the dogs to make the blockage more viewable in xray will help move things along and surgery isn't needed (been through that one too).
If he continues to have problems, call a vet and see if they'll work out a payment plan. I have a credit card just for dog emergencies.
My concern is that (and I'm sorry) maybe you should try to rehome the dog until your better financially prepared to care for him properly. I spend several thousand dollars a year on my dogs - they tend to get in to trouble! Your's doesn't sound any different. Unless you're willing to be with the dog 24 hrs to watch everything he's getting into, and crate him when you cannot - you're going to have this kind of stuff crop up. You may be saving him from the shelter but you could also kill him with your kindness. (plus you need to be able to take care of yourself too
).
Make sure there is no open antifreeze available for him to get into, it's toxic to dogs. Also, if you have a pond, in warm climates or during spring alge blooms are also highly toxic to dogs. Lastly, becareful not to allow vigerous activity before or 1 hr after feeding (drinking alot of water etc) - this can cause bloat - bloat is caused by twisting of the stomach, it's serious and can kill a dog within hours.
Good luck with your pup.