Is it normal to feel like im going to pass out after bending over & reaching while holding breath for about 5 seconds?doesnt happen every time.also, happened while sitting in my chair after inhaling deep yawn, exhaling hard breath for a few seconds?

Valsalva-like : Your actions raise intrathoracic pressure affecting coronary artery flow briefly, and causes feedback vasovagal mechanisms resulting in your faintness. You could be more sensitive, but there could be some underlying cardiac or pulmonary issues that are starting to present. So, to be on the safe side, have your doctor evaluate your current health status.