Your article on the itchy chin and neck hit home. Nearly 7 years ago, I was diagnosed with Histamine Intolerance, and a couple years later, with MCAS.
After going on a low histamine diet, many things improved drastically, such as migraines, brainfog, and IBS-D. What I didn't expect was that my asthma greatly improved as well! I still take Singulair, but no longer need my steroid or rescue inhalers daily - I go for several weeks without needing them, only digging them out of the drawer when there's a wildfire filling the air with smoke or I have a respiratory infection.
The itchy/burning/flushing reaction from chin to decolletage is an early warning sign that I need to cut back on the medium-histamine foods immediately. It is often preceded by sudden swelling and congestion of my nasal passages, another useful signal.
If anyone else wants to pursue this avenue, my doctor recommends the book "Is Food Making You Sick", which presents much good information as well as how to start the elimination phase (aka VERY low histamine diet). It is the weirdest, most PITA diet I have ever encountered, but there's no arguing with success!