Differentiating Carcinoid syndrome from MCAS?

Hi UK based where mcas is poorly understood

I have been diagnoses with autoimmune gastritis in the last few weeks
Symptoms over the last few years have been scary varied and no one joined them up to see they were connected
Dry eyes , puffy eyelids , poor night vision, pain on bright lights. Better now on viscotears and oil based eye drops
Then arthritic pain in knees ankles
Neuralgia pain like pins and needles stinging burning stabbing in arms hand legs feet then in face back etc
Rapid heart beat particularly at night whooshing noise in ears
Rapid heart rate randomly I'm day ie 134 at rest but inconsistent
Flushing salmon pink or red blotchy face neck and upper arms to elbows both sides
Dry flush with heat 1 min or less
Breathlessness
Dry cough
Worse after food exercise stress and randomly too
Flush 15x or more times a day
Allergy type symptoms as above not just after food
Hives in throat , red tongue tingling in lips
24hr urine test showed 4 x adrenaline
24 hrs heart monitor showed extra heart beats but not tachycardia enough for a pattern
Referred to rheumatology who diagnose with zero negative inflammatory arthritis
Changes in finger synovitis
Placed on sulphalazine 2 x 2 per day July 2022
Heart palpatations continued but started to ease on the anti inflammatory
Fatigued
Ultra sound scan 2023 showed fatty liver disease and high bad LDh cholestrol
This hasn't altered despite no sugar no alcohol no fats eating v cleanly ie low carbs and lots of vegetables and proteins low in fat

Always had low BP then suddenly bp spikes and drops . All over the place
Crisis episodes after naproxen for 4 days March 2022
It inhibits doa enzyme and I felt literally poisoned. Heart rate up nauseous, fast breathing, clammy bp 177/100. TOLD NOT to take again
Given betablockers May 2022 for heart palpatations. Blocks adrenaline and had almost an anaphylactic shock ie throat swelling lips and breathlessness . Had to phone emergency line and told to take and anti histamine which resolved it .
Acid reflux
Took ant acids
Took prednisilone April to June 2022 before rheumatologist gave advice June 2022. Made symptoms worse ie allergic and heart Offered 15mg but felt so ill reduced to 5 mg per day
Slightly elevated Alt enzymes in liver bloods
Sodium in blood kidney results are at top end of normal
Ultra sound scan thyroid nodules . Tsh goes down and then normalises then goes down
Gp seeing all symptoms separately and isn't aware of all being connected which has always been my feeling
ESR levels move form 17 to 22
Borderline rheumatoid factor ie 14
Crp normal
January started more allergies to foods ..got worse and worse . Worked out it was histamine. Went onto zero histamine regime and it improved somewhat but not completely ..Still have flushing as day goes on but has lessened. But breathlessness all day long and intermittent Dry cough. Anti histamine loratadine H1 helps with allergic type responses. Can't tolerate a trying with histamine now at all. Lost a lot of weight . Weight now stabilised. I has zero appetite until I went onto zero histamine diet.
Had scary incident october 2022
Bp went up expedentially to 206/107 ended up in an urgent care centre
Returned and put on a calcium blocker BP tablet.

Frightened of my body and what it was doing
Presently zero histamine foods
Awaiting endocrinology appointment
Flushing but reduced
Breathlessness all the time
Fatigued
Nerve pain 24 hrs a day

In the past few years started to find I was having reactions to dried cranberries, black caffinated tea . Past allergies lemons limes feathers dust.

Always had very bad period pains
Life is tough . Stopped working at the moment

Been to Gp and I siad I think it may be carcinoid syndrome associated with a possible foregut net tumour producing histamine ....

Or could it be mast.cell activation syndrome?
Had muscle and bone pain for 12 yrs
Had vitamin D issues ie lowest 2011 was 9
Now on vitamin D and calcium daily Now 65
Bone density scan February 2023 oestepenia
Awaiting echocariogram and referred to cardiology consultant all at my request
Neurophils lower than normal ie 1.4 ? Sulphalazine or ? Overall white blood cell count 3.6 so lower than normal
Red blood count normal
Question I have is
How do yoy determine if carcinoid syndrome.vs mast cell activation

I've finally got a referral to a specialist Oncologist endocrinologist to assess for carcinoid syndrome
Who deals with mcast ? In the UK seems v hard to get any help.or a diagnosis
What tests would I need for mcast ?

Advice much appreciated
Been like this for 2.5 years and got much worse recently

Worst part is not been believed and feeling hopeless and helpless and scared especially heart, bp, nerve pains

Thank you