Wow, thought I was the only one having med issues? I get vertigo, which is not a good thing when running down a single track - even as slow as I go! Went through all the tests, heart, brain, blood pressure etc. And, while I do have high blood pressure, mine turned out to be Migraines with Vertigo/Aura which causes me to get very dizzy and vision goes to crap! When I was younger I suffered from regular headache type migraines - maybe once or twice a month, brought about by stress and now they have morphed into the vertigo and NO HEADACHE PAIN! Just Google Migraines with vertigo or aura and see some of the other symptoms that they can cause.
I had to cancel a ride yesterday because of this crap - Hopes this helps.... good luck!