First, I want to thank everyone who commented to me about finding ways to help out with Madison and the vet situation.
I took him yesterday and I THINK it was good news...or at least it will hopefully be!
She thinks (without doing bloodwork) that he's got a gastritis (that much I knew, just not the extent), and several behaviors and symptoms point to that...she thinks that giving Pepcid AC (regular,not chewable and not the new Max. strength), 1/2 tab (he turned out to be 6.8 lbs

, he's still thin, but I was shocked!!) each day for 30 days and changing his diet to a higher fiber, low fat one will make a big difference. Then there's a sort of weaning of the Pepcid if he does well on that. She said that the generic formula is just as good as the brand one.
So, that was EXCELLENT news in my eyes!
Am waiting for the fecal results, so don't know about that yet.
I asked about collapsing trachea, but she says no~ he's got "reverse sneezing" or "snuffles" related to the esophageal reflux, which also could be related to why he does this "downward dog" pose frequently (she said that indicates a gastric problem of some sort) and she thinks his teeth have more tartar than he should have for his age (she thinks he's probably about 2 yrs old). These all should hopefully improve, or resolve, with the improvement of his gastritis/esophageal reflux. I am posting all this mainly in case anyone else sees these symptoms in their dogs....but she also said it COULD be a pancreatitis except b/c it seems to be cyclical, it's hopefully not.
I also asked about LP; she said "no" to that also....unfortunately, she says something is going on with his HIP

, but it doesn't bother him now and she can't really tell without an x-ray, so she said when I'm ready we can do that later.
So, all in all, it's at least encouraging news. And it only cost me $100!!! I was ECSTATIC; not only is he getting what he needs, it was much less costly than what I had anticipated.
He's doing fine today too, was up at around 3 am, and I was afraid it was going to start all over again, but .....he's been fine all day and is eating and playing just like usual.
I'm keeping my fingers crossed that he'll continue to improve. OH...also, she said that his hair IS sparse but it could be b/c he was in starvation mode; and that it takes 3-4 months to come back from that, so we'll see if his coat changes any!
Thanks to everyone on YT for their support and positive thoughts! You're the BEST!!!!