I'm 51 And Have Had High Blood Pressue For The

I'm 51 and have had high blood pressue for the past 10 yrs. I'm on Lisinop/hctz 25mg. I have recently begin to have strange headaches along with feeling very sick to my stomach and feels like my eyes start fluttering like I'm gonna pass out at the same time, I begin to check my blood pressure and it was lower than its ever been, it was 107/59 and my pulse was 90. What could be causing this and is it dangerious.