Orthostatic hypotension.when i stand up i go blind. several times, my whole body has twitched. failed table tilt test, as well. low bp & high hr. help

Needs Evaluation: With yr symptoms it is clear that you have Orthostatic Hypotension and it needs to be investgated in detail.The causes include 1Dehydration due to any cause like not drinking enough fluids or loss due to vomiting/diahhrea 2Heart Disease like low heart rate but your HR is high 3After meals Hypotension 4Nervous System Diseases like Lew Body Dementia 5EndocrineDisorders Addison's Disease,Hypoglycemia

Orthostatic Hypotens: Multiple causes of orthostatic hypotension include dehydration, cardiac issues, and carotid blood flow issues. Your doc should start a work up.

POTS: sounds like POTS....please see an electrophysiologist for counseling and treatment. Other than avoiding dehydration, medicines such as florinef (fludrocortisone) or midodrine or beta-blockers may be indicated. But you need to be evaluated and under the care of an electrophysiologist.