My Doctors Are Confused

I come to you after a long 2 months, I've been bedridden with no answers & Cardiologists Are Lost. "Diagnosed" Symptoms: NSVT, PVCs, SOB, POTS, Tinnitus, Severe Fatigue, chest pain. Tests completed: Echo: Normal, Trivial MR Treadmill: Norm, Stopped at 3 mins b/c of SOB ECG: SVT, NSVT, PVC TSH: Norm HS-CRP, BNP, D-Dimer: Norm Electrolytes: Norm Ferritin: Slightly Low MRI: To Be Done Anxiety: Ruled Out I cant walk more than 20 steps without severe SOB. What else can i test/do?