What a cutie Molly is... but so sorry to hear that she is having these issues.
Regarding the cost of the tests, unfortunately, they USED to be around $125 (TLI) but those days are pretty much gone. Depending on where you live in the country, the cost will vary, but it appears that the price nowadays is anywhere between $250 and $350. Someone even quoted me a price of $400, but that was in Calif.
In short, if possible, you really should have Molly properly tested. But the fact that you paid very close attention to what appears to set her off and what appears to help has given you EXCELLENT clues on what to test for
Good job Molly's mom! I wish more folks were as observant and keep good records (very helpful!)
The glandular supplement that you are giving Molly... well, Madelon's post summed it up perfectly..... If this is EPI it really is not helping, and ditto for Pancreatitis... depending on the degree of the condition. There are some excellent ingredients in this product, but on the flip side, there are ingredients in this product that simply is adverse to a dog dealing with EPI and there are other ingredients in the product that are adverse ingredients to a dog dealing with Pancreatitis. IN the end, it is often cheaper to spend the money to have the proper test done vs. spending money trying one thing after another trying to guess what might work and what is going on.
My next step would be to test for either EPI or Pancreatitis. The Schebo test is ONLY an indication test... IMHO...I would do the TLI test for EPI first, especially with the stinky stool, but then again, If your dog is doing the prayer stance, maybe i would do the PLI test first.
Unfortunately, in either case (EPI or chronic pancreatitis) Molly would very likely respond positively to the enzymes....sometimes even dogs with IBD will temporarily respond positively to enzymes. However(just as an example).. if Molly is having an acute pancreatitis attack you do not want to give enzymes at that time- - i am simply mentioning these other examples of why i like to stress the importance of running the proper tests, when possible............but we totally understand the expense. We all can only do the best that we can when we can.
Regarding the bright red blood that you observed...how it came/went and based on what you posted and what your vet said (tested for bacterial and there was none).... i strongly suspect your dog had colitis . As Patsy mentioned, this will sometimes clear up on it's own if not too bad, but at other times, an antibiotic is needed. And with colitis... it can be a LOT of bright red blood...(my dog Rico had Colitis once where bright red blood was shooting from his rectum as if it was from a hose! )..The most common cause though is not necessarily bacterial (although it can happen from parasites) but rather Colitis can often be stress-related for whatever reason.... the typical anti for colitis is metronidazole.... i personally had tylan on hand, and althou not the #1 choice for colitis, it will still work (which it did in my case) although not as well as the metro.
Also, Psyllium can really help firm up the stools... and i know you said you are using very little... but Molly is also a very little dog... Psyllium can be very harsh.... so i just want to reiterate to really, really REALLY please be careful. SLippery Elm is a much more gentle way to go vs. Psyllium for the same end result. My thought is to use only one or the other, not both (if i read your post correctly)... or if not too loose, you can always try a tsp of canned pumpkin.
Hope this info helps a little and that you figure out what is really going on with little Molly soon.
Please keep us posted.