The dog still has the cough, he isn't skinny anymore, his stomach area is as a pregnant female. 3 different vets have given me 3 different answers to what wrong. All the dogs have been treated for worms & there aren't any signs of worms in their stools. The dog in question is active but I can tell he is uncomfortable

Sounds to me (and this is only opinion) that is could be his digestive system.
Does he have rather bad gas?

I would play around with his food, try feeding a high quality all natural food.

Ive been feeding all my dogs Iams for the last 2 years. I have 6 of the same breed, pitbul/shar pei mix. None of the dogs have bad gas.

The only options I can think of is to try another vet or switch foods.
The vet option seems not to have worked for you.
Iams is supposedly not one of the best foods (according to sites like Dog Food Analysis - Reviews of kibble) I would try switching to a natural food or even consider the barf diet.

Hopefully others will come on to give you some more suggestions.

How long has your dog been bloated for?
Does your dog do or have any of these symptoms?
Try to throw up
- Drool
- Have grey or white gums
- Have difficulty breathing
- Pace
- Have gurgling noises coming from his stomach
Have they (the Vets) done any x rays?
Has the vet mentioned or checked for Bloat, Torsion, Gastric dilatation-volvulus (GDV)
Have they given any steroids Antibiotics or antiarrythmics?
If your dog has a tendency toward bloating, you could try giving him small amounts of food throughout the day, rather than allowing him to gulp down large meals. It may also help to keep other pets away from him as he eats; some dogs feel they have to eat fast with humans
or other animals are around, because they fear someone else will try to eat their food. So let him eat in a room by himself.
And I am sure they have given treatment for hookworms and other worms right? How many treatments?
Bloat can be life threatening to dogs.
You could try a holistic diet. I feed Iams, it used to be vet approved and recommended, but they stopped because Iams stopped buying from one source only, and bought from who ever was cheaper. There for the Vets could not stamp their approval on the food. Lots of dogs I know who have skin conditions can not eat Iams, I think it is just the commercial brand in general.


On side note,I am not a vet nor do I practice animal medicine, I am only giving you what knowledge I have on the subject.
I would try another vet in your case.

What have the vets done in the ways of diagnostics? Blood? X-rays?