Yogurt Failure

Ug, I'm on the fringe of a major yogurt disappointment. I recently switched to Greek yogurt for the extra protein and other health benefits. I've tried a handful of varieties by Oikos (Stoneyfield) and Chobani. Some have been very good but in the past week I've had some major disappointment. Last week I had 2 different containers of the fat free blueberry Oikos that were so runny they weren't even the consistency of regular yogurt. Greek yogurt is supposed to be thicker! Stirring it did not help at all. It tasted okay though. I've had a couple of other containers of the Oikos with fruit in it in the same state prior to last week. Today I noticed that my container of strawberry Chobani had a bit of a bloated lid although it was sealed very tightly. When I finally pried it open at lunch time I noticed a similar bit of runny behavior as I had in the Oikos but with some thicker chunks so I stirred it up really well. When I ate it though it tasted really funny almost as if it was burning my tongue. Needless to say, I threw it away although my paranoid mind seems to now think my stomach is upset from the 2 bites that I ate. At $1.39 to $1.59 per container this stuff is too expensive to be throwing away. The sell by date on it was late October and I can't seem to find anything online that explains why this keeps happening to me. My only consistent success in either brand has been with the honey and vanilla varieties. I suppose I should stick to them and add my own fruit since whatever they are doing to put fruit on the bottom seems to be ruining the yogurt.  Image from http://www.cookinglight.com