When my bp, which had always been VERY low, rather suddenly skyro...

Whenever bp suddenly goes up, there is probably an underlying cause that should be investigated. Yet most physicians are perfectly happy to diagnose hbp - as if that ever comes on suddenly. In my case, they diagnosed hbp, gave me lisinopril, which confused things because of the enormous side effects, which took years to recover from. About 2 years after the hbp dianosis, I finally discovered that I had gallstones clogging my bile ducts - this was the cause of the sudden spike; it was not hbp. Even if diagnosed with hbp (the kind that comes on slowly over a lifetime) and have had it for years, with a sudden spike, I would be very reluctant to accept a diagnosis of "well, you just need to double your dose". Spikes in BP are a sign of some other underlying problem that needs attention, not ordinary HBP.