Hello and welcome from me too. I could be a stronger batch in the last prescription of trilostane, it could be both drugs together aren't working for her (Simplicef and trilostane) but I would venture to guess that not feeling good with a bout of pancreatis and her cortisol being lower than it is normal is making her feel awful. This could contribute to a panic type of breathing (my thoughts only)
So what I'd do is no trilostane until the pancreas is normal, she is eating fine and no diarrhea. Then start back at 10/5 or 5/5 dosage to see how she does and then retest after starting at the normal protocol.
To have a firm diagnosis of protein loss via urine, you want to have 3 consistent UPC test, taking about 2 weeks apart. I prefer first urine of the day, as that is easiest and you can do a drop off at your close vet and have them run the test. If all 3 consistently test high, then you can look into a food with lower protein in it and see how that works. (they should have a dietician at the VCA)
She might be hanging her head due to the pancrease as quite often you will see a sort of hunch with that, from the pain and hurting.