Why would a dr. put you on high blood pressure pills when you have low blood pressure

If you suffer hypertension (abnormally high blood pressure), we go through a standard regimen that eliminates any potential causes for the condition before we even think about prescribing antihypertensives: these drugs are potentially lethal if abused.  Alpha and Beta blockers can cause cardiac arrest in the case of any overdose.  To reverse the effect we must inject (sometimes massive) doses of epinephrine directly into the heart.  

If you suffer chronic hypotension (abnormally low blood pressure) we also eliminate any cause for the condition before we consider medication.  Hypotension is much easier to treat as we prescribe beta adrenergic stimulators, which are much safer and have a much lower potential for complications.

Quite often the best remedy is to change one's diet, lifestyle, etc.  The simplest and most natural remedies are ALWAYS the best.

Don't know your history but on the face of it, that seems strange. Are you sure it's a high blood pressure medicine? Do you know the name of the medicine? The most common treatments for LBP, if one is required, are drugs called fludrocortisone and midodrine.

I'd get a 2nd opinion anyway.

Could it be Lasix (furosemide)?  That might be prescribed for congestive heart failure.