Thanks for your question on HCM.
I can understand your situation and problem.
Yes, swollen glands can cause breathing difficulty especially in night.
In night, due to supine position, glands will narrow the upper airways and thus you can have breathing problem and thick mucus.
But in your case, we should rule out
bronchitis also.
Because bronchitis can cause
wheezing, breathing difficulty and thick mucus production.
So get done PFT (Pulmonary Function Test) to rule out bronchitis.
If PFT is normal then no need to worry.
Your symptoms are due to swollen glands only.
You may need antibiotics, anti
histamine and anti inflammatory drugs.