38F, Italy, multi-system symptoms for 2 months, no diagnosis despite 3 ER visits. Looking for insights.

Reason for post: Persistent multi-system symptoms for approximately 2 months, no definitive diagnosis despite 3 ER visits and cardiology evaluation.

Main symptoms:

Recurrent nocturnal sinus tachycardia (3-4am), with trembling and sensation of adrenaline surge

Sinus tachycardia on minimal exertion (e.g. walking slowly uphill)

Low blood pressure, unstable during symptomatic period

Nocturnal acid reflux, significant digestive difficulties

Immediate post-prandial bowel evacuation, chronic abdominal bloating

Urinary frequency with sensation of incomplete emptying

Generalized joint hypermobility (lifelong)

Fibromyalgia (existing diagnosis)

IUD nearing expiration

Prolonged period of chronic stress with two close bereavements in the last 9 months

I also experience recurrent bilateral ear muffling specifically while eating and during minimal exertion (slow uphill walking), suggesting transient reduced blood flow to the head during both digestive and exertional blood pooling.

Tests already done:

Multiple cardiology evaluations: sinus tachycardia confirmed, structural heart disease excluded

Echocardiogram: mild tricuspid insufficiency, tripartite aortic valve with mildly thickened leaflets, minimal non-stenotic insufficiency, PAPs within normal range

High-sensitivity Troponin T: 5.34 ng/L (normal, <14)

D-dimer: 500 ng/mL (reference <300), not followed up with chest imaging (during panic attack)

WBC: 14.8 (elevated, in context of active dental infection and cough)

Fasting glucose: 106 mg/dL (upper limit of normal) (during panic attack)

Potassium: 3.6 mmol/L (low-normal)

Coagulation, liver and kidney function: within normal range

TSH: within normal range (historical)

Current medications:

Alprazolam (Xanax) drops, for 3 weeks, no improvement on cardiac symptoms

Magnesium citrate/pidolate/carbonate supplement (evening)

Diagnostic hypothesis to explore: The combination of joint hypermobility, dysautonomia, postural tachycardia, low blood pressure, fibromyalgia, gastrointestinal dysmotility, and bladder dysfunction is consistent with hypermobile Ehlers-Danlos Syndrome (hEDS) or Hypermobility Spectrum Disorder (HSD) with associated dysautonomia (POTS-like pattern). The prolonged period of chronic stress is a likely trigger for autonomic decompensation in an already vulnerable system.

What I'm specifically looking for:

Has anyone had a similar symptom cluster and received a diagnosis?

Any experience with hEDS/HSD and dysautonomia presenting this way?

Which specialists were most useful in getting a diagnosis?

Any experience with POTS tilt table testing in Italy specifically?