Hate to be the skeptic but this is a great link to check out

http://en.wikipedia.org/wiki/Orb_%28paranormal%29

along with this one

http://www.sgha.net/orbs.html

However if you are seeing like actual white floating balls or flashs of light I would recommend seeing a doctor. Many things like high blood pressure, cataracts, retinal damage, etc. can cause these effects. Albeit, the experiences may seem "spiritual" there may very well be an underlying cause. It's better to be safe then to be sorry. Either way, hope you figure it out. ^_^