Hi there! I am so glad you posted here before sanding down the bridge, yourself. This is never something I would recommend to a student. Bridge adjustments and sanding are something much better left to a skilled luthier, or a player who already has experience with adjusting their own instrument.
May I ask, are you only having issues with pain on the D-string, or is it because you’re primarily playing repertoire on that string? How long have you been playing violin?
Issues with a particular string can be caused by a number of things: string tension, hand/finger position, tension, bridge height, etc. I think the best way to diagnose is to maybe get a good look at it. Would you mind posting a picture of your string from several angles, including one where the camera is at the bottom of the instrument looking directly on the bridge?
Hopefully we can help you work through what’s going on!
Violin Tutor Pro Instructor