What happened to my Ginger Ale!?

I made 5 gallons (kegged it and force carbed) of delicious ginger ale (non-alcoholic) for the fiance and my nephews and neices. It was delicious for a month or so and then all of the sudden I went for a pour and a bunch of ginger/lime sludge came out. I figured "Wow, we went through it already?" So I lifed the keg out and to my surprise, it was still about 1/3rd full. I went for another pour and a bit more sludge came out but then it turned to almost water clear. I took a sip and it pretty much tasted like flat, dirty, water... Now depending on the day, it either comes out as sludge or that murkey water and still has no flavor.

I'm confused!! It seems the ginger ale has separated and somehow lost all carbonation even though the keg is still under pressure (25psi). What's going on?!!?

Help!