If your symptoms or worsening, don’t get a tilt table test. Doctors have been phasing this out as it can be dangerous. Bring all of your concerns up with your PCP and ask for a referral to either/both a cardiologist or neurologist. They should be aware that all three of these disorders are very common comorbidities. Diagnosis-wise, it’s safest to get a differential diagnosis by getting an echocardiogram and a Holter monitor for a few days to rule out any other possible issues.