> Can you tell me what is going on here?? <
You can't measure a room one day, then measure again another day - with a different microphone no less - and expect a valid apples-to-apples comparison. The main problem is the low frequency response in a room, even when treated with bass traps, varies a lot over very small distances. Even four inches away the response will be very different. I'm sure this is the main reason for the large changes.
Also, a better way to assess the improvement from adding bass traps is to look at waterfall graphs. This way you can see the reduced ringing after adding traps, even if the magnitude of the response at different frequencies changes. Since you have the data in REW form there's no need to measure again - just switch to the waterfall plots.
--Ethan