I'm sorry to hear that you're having this issue.
Unfortunately, I'm not able to diagnose without inspecting the unit.
My tv is 1.5 years old & out of warranty, and in the past few weeks has developed a picture quality issue. When I first turn the tv on, the picture is fine. But within about 10 minutes, the screen turns greenish - there are still other colors present, it's an oily green shadow effect. I know it's going to cost a fortune to bring a technician to my home to fix - I'm wondering if its possible to identify the problem before they come out to save a second trip.