so several times a week now i will stand up and get a head rush - you know, where your head feels light and kinda begins to pulsate and your vision narrows and whatnot. i've been told this results from low blood pressure or a sudden drop in blood pressure. what could lead to this? it's been going on for the last 2-3 weeks.
some background: i've always been active but recently started training for a triathlon so i now workout in some form 6 days a week. i'm 5'10" and since january i've gone from 180 to 170. my resting HR has gone from 70 to 60. i was vegetarian for 9 years, vegan for 3, and recently started eating fish again (still no dairy or eggs). i have no idea how many calories i consume daily but i'm fairly sure it's enough, and it's generally very healthy i think.
any input would be appreciated. i've also been meaning to go get a check-up and full bloodwork done just for standard reasons so maybe i'll actually do that now.