My fiance feels dizzy some times. She normaly has low bp. She has no other symptomes. She spends a lot of time on computer.?

Sitting? Sitting for long periods usually measns two things: blood pooling in the legs; and time spent sitting at a computer means less leg muscle tone. Both will contribute to "orthostatic" hypotension, causing dizziness. Your age suggests she is younger, so more serious issues are unlikely. She needs to take breaks and engage in some exercise orr sporting activity she enjoys. Also stay hydrated!