Sure sounds like MCAS.
MCAS is a syndrome, meaning a collection of symptoms, not a hard-and-fast disease. (Although there are mast cell diseases, such as mastocytosis.) MCAS is a body process that occurs in many people with Lyme, mold exposure, and many other conditions. It's good to know if it is something that happens to you, but in very mild cases, it's not super important.
When you have Lyme and are treating it antimicrobially, MCAS can exaggerate a herx and add symptoms to it. In more severe cases, it can cause serious symptoms, such as blood pressure drops and respiratory distress, but it doesn't sound like that's the case for you. You might consider taking mast cell stabilizers along with your other supplements and/or meds, since sometimes an easier herx or reduced overall inflammation can make treatment go faster and be easier to manage.
MCAS treatment options:
Supplements: quercetin, curcumin, stinging nettle, cannabis (including CBD-only formulas)
OTC drugs: H1 blockers, H2 blockers, Benadryl
Rx drugs: ketotifen, cromolyn sodium
Low-histamine diet
DNRS limbic system retraining
Avoiding triggers helps me more than anything. Triggers vary from person to person. My absolute biggest one is fermented food, including things you might not expect, like a very ripe banana. But there are a lot of triggers, and they can be cumulative, meaning sometimes if I have not been dealing with many triggers, then a bite of fermented food might be something I can manage.
Common triggers:
Heat, sweating, hot showers
Cold, shivering
Cardio exercise, exertion, physical stress
Emotional or mental stress, anxiety
Abrasive fabrics, skin manipulation
High-histamine foods (ferments, citrus, aged foods, alcohol, coffee, tomatoes, etc.)
Mold and mycotoxin exposure
Inflammatory reactions (such as a herx, infection, or injury)
Allergens (pollen, outdoor molds, dust, dander, air pollution)
Irritants (cleaning products, body products, fragrances, detergents, toxic fumes)
Most people do not have all of the possible MCAS symptoms and may only have a couple of them. Common MCAS symptoms vary but can include:
Skin symptoms (flushing, itching, rashes, burning, redness, dermatographia, hives)
GI issues (cramping, diarrhea, reflux, nausea, throat tightness)
Anxiety, irritability
Fatigue
Brain fog
Headaches
Neurological issues (neuropathy, tingling, twitching, pains, POTS)
Cardiovascular symptoms (blood pressure change, tachycardia)
Respiratory symptoms (scratchy throat, congestion, asthma, anaphylaxis)
There is a lot of overlap with what people think of as Lyme symptoms, which is why treatment can be so helpful. If half of your Lyme symptoms really come from MCAS, then treating it can yield quite an improvement in quality of life. You still have to deal with the underlying dysfunction that causes the MCAS, but it's nice to feel better!
I highly recommend the book Toxic by Neil Nathan. It's excellent for figuring out where to start and demystifying the more complex cases.