1) See a doctor<br />
2) How do you know what it is?<br />
3) There is "new" thinking about blood pressure. Used to be either the high or low number [sorry I forgot which] was considered more important, now it's the other way around. Most recently, and most sensible to me is "pulse pressure - the difference between the high and low. mzdivine is correct in saying 220/180 is worse than 120/80 since overall higher pressures outweigh equal pulse pressures, but the "pulse pressure" Intrudelvr cites is equal to mzdivine', i.e. (220 - 180) = (120 -80) = 40, and yours is (99 - 55) = 44, virtually the same!.<br />
4) The lower number is the amount of pressure inside the artery while the heart is relaxed that equals the body"s internal ambient pressure to collapse the vein/artery altogether and results in zero net difference [the vein doesn't collapse or explode, just is neutral]. When the heart "pulses" to push blood through, of course pressure will increase and if too much leads to stroke. OK so far? As long as the pulse pressure isn't large OR tiny UR probably alright, but this is NOT medical advice!<br />
A person with 170/70 might be thought to be healthier than one with 170/100, but IF pulse theory is correct, the pulse pressure person of 70 is better off than the one with 100, since my common sense tells me the heart REALLY has to push the blood harder, which can't be good.<br />
5) Refer to 1)..... :)