Since you are asking for advice... I think it might be wise to deal with this in phases... That is, you have to solve some problems in the short term, while looking toward long term goals.
I don't have Borrelia, but my daughter has a chronic case that long term antibiotics didn't help. We've learned in the long run, 10 pass ozone seems to be the most effective in beating it back, with several sessions closer together and a booster every 3 months.
MCAS can be genetic or autoimmune. My doctor, a top ME/CFS specialist, tested me for the genetic KIT SNPs and found none, so he thinks mine is autoimmune, triggered by one or more of my infections. He found I had high prostaglandin D2 and Chromagranin A to diagnose it. The tests must be kept cold to be accurate.
My histamine and tryptase, the 2 most common tests, were low, and they can be low while still having MCAS, so they were not helpful. I believe this is because I avoid my food allergens, and an on a fine tuned methylation protocol with lots of vitamin C, B5, quercetin and curcumin to help clear out undesirable things (allergens, toxins, and metabolic waste).
Then, he put me on ketotifen, cromolyn sodium, ranitidine, and diphenhydramine to help my gut symptoms - I had nausea a lot of the time and painful intestines. He mentioned that he's consulted with Dr. Afrin, one of the 2 top specialists (the other is Dr. Theoharides who has an informative website), and th St if my symptoms didn't calm down, that Gleevec might be helpful - he'd put 4 patients on it so far and it worked wonders. It's also quite expensive, so could be out of reach for many.
Attached is a paper listing a lot of drugs and natural substances (like curcumin, quercetin, and vitamin C) that play different roles in MCAS treatment. The second attachment is a case study of a woman that was the subject of this week's Health Rising article - her MCAS, POTS, and SIBO were successfully treated with Iow dose Naltrexone, IVIG, and Rifaximin.the others here have used similar strategies, on a full gamut of MCAS and POTS meds, but able to reduce them as the autoimmunity lessened. I've found benefit from Naltrexone and IVIG over the past year as in the case study.
As for digestion and diet, being on a whole food, anti inflammatory diet can be helpful while you heal your gut. My doctor suggested I-glutamine to rebuild my gut lining after chemotherapy, and high quality probiotics, digestive enzymes, and stomach acid can be helpful. A good book that can help you troubleshoot is "The Food Intolerance Bible" by Anthony Hayne. If your digestive sysyem is happier, you won't have partially digested food particles leaking into your bloodstream, which your immune system reacts to.
A DNA stool test mught help you identify any parasites, fungi or viruses, in addition to an unfortunate mix of bacteria in your intestines, and treating whayever is found would be helpful, too. In my family, different members have had Candida, c. difficile, who tells, h. pylori, roundworms, pinworms, and blastocyst is hominis... we all are celiac and it seems that once you have an unhappy gut, it leaves you open to opportunistic infections, riling up the immune system, causing "leaky gut" and causing malabsorption of nutrients.
The last thing is to check your nutritional status. If all of this has been going on for A while, you may be deficient in key nutrients like amino acids, B vitamins, anti oxidants, lipids and trace minerals, all needed for your body to repair itself and to run your immune system.
All of this must seem overwhelming, but ideally, working with a knowledgeable functional medicine doctor, or through self help with the book I mentioned and the many good resources on the internet these days, and at least a cooperative GP that will run the tests you need, you can sort all of this out, and strengthen your body to minimize your symptoms.
I'm not a doctor, but have been through much of this myself, and it does get easier as one works their way through this, with the reward of eating a broader diet, being able to reduce meds, and having fewer symptoms.
Hang in there!
