So i opened up a bottle of home brew that had been lagering for a few months. When i opened it and pour it into a glass is was perfectly clear with nice carbonation. Then within 5-10 minutes it was cloudy, and the sort of cloudy you get at the end of a barrel, any ideas why??
As the other answers suggested, it might be yeast in suspension, and that would be my bet too.
You probably noticed that the beer was clear when you poured your first glass. But the beer in the bottom of your bottle always* contains some yeast sediment. When you poured that your beer turned cloudy.
I know of no other explanation for the phenomenon you described other than this.
*unless you filtered your brew with the specific purpose of avoiding this, or lagered for a very long time and used forced carbonation.
I thought Chill Haze, but that is usually when the beer is cold and unfiltered; ss the beer warms up the haze goes away.
Here is a BYO article that you can read on Chill Haze. Maybe it has a solution for you: http://byo.com/hops/item/486-conquer-chill-haze
A haze that appears when the beer warms up is strange...
You poured it, so it wasn't yeast in the bottom of the bottle that was roused due to drinking & carbonation...
Potentially it is yeast disturbed when you pour that over the course of 5-10 min clumps together and clouds the beers, or potentially bacteria, if the later I would expect the beer to be unpleasant.
is the beer drinkable, if so I suspect you have some yeast floating around.