I think dairy is considered inflammatory, probably more for some than others - and certainly it causes mucus - and inflammation causes mucus. I'm not overly strict because I eat pretty well and for me, carbs are the big inflammatory evil. I can tell by my digestion....If you have a sensitivity or digestive issue with a certain food group, try taking a break from it for a while.
Coconut milk and almond milk are decent substitutes. Soy milk is ok too - but soy is considered bad for thyroid and hormone issues.
Dan, don't blame yourself - you are doing all you can to get info and figure this out, and it's no small task...they don't make it easy for us to get info on nutrition in our food, medical care, etc. It's been ten years of learning for me...
I think one of the biggest stresses is sleep deprivation from bad sleep. It's just debilitating for me! I am a different person when I can get ok sleep.