Hi Swati,
I ran into this problem with the Score was Changed trigger. I wanted to know when a score increased by 100 points so I could send sales an alert, but the trigger wouldn't work. The problem seemed to be that other scores would kick off before the trigger was processed. Opened a ticket with support, but we weren't able to resolve. The data value changes field can be used, but it can only detect when a score reaches a threshold vs increases by a certain number of points. It doesn't seem like that is what you are trrying to measure.
In the end, I used a different trigger altogether that ran parallel with the score change.
If you happen to get this score was changed trigger to work, I would be very interested in learning how.
Best,
-Jamie