Every time I stand up I blackout for 5 seconds but I'm still conscience. I feel like I'm going to faint, dizzy, lightheaded. I have fainted twice.

Fainting. This is orthostatic hypotension - your blood pressure drops when you rise too quickly decreasing oxygen in the brain. Given this is a recurring experience it is worth having an evaluation by a doctor. There are some conditions and medications that influence its occurrence. Depending on the cause, you may be instructed in techniques such as compressing the abdomen and legs while rising and standing.