Until your GP manages to get you into some cardiovascular function tests, you might be wise to avoid physical exertions that so seriously tax and wind you - and stick with some steady but less intensive activities that do not send you into such severe “hypoxia”. Take it especially easy in the morning upon waking. It takes around 40 minutes for your system to stabilize in terms of hormones/neurotransmitters.
A large proportion of heart attacks (which are associated with rapid and significant increases in BP) take place within those first 40 minutes of waking, and a large proportion of those events occur on (for many, stressful) Monday mornings. I (myself) like to start slow with the Nicotine after waking, sipping slowly and gradually. Absorption of Nicotine is relatively slow when vaping (the free-base, anyway), which has a net protective effect (relative to a cig, which raises systolic BP by 5-10 points or so rapidly). Watch those salts.
Strokes, on the other hand, are associated with relatively rapid and significant decreases in BP. Blood pressure numbers as measured can vary significantly - usually reading higher when tested at physicians’ offices (the so-called “white-coat” syndrome). The “basal” (just after waking) reading can be the most instructive. BP gradually increases during sleep, is usually in the higher ranges upon waking, and typically (on average) decreases throughout the day towards a minimum when one is exhausted and initiates sleep.