I once started getting a buzzing sound when i was playing. It turned out to be the silver winding on my D string was coming loose. I didn't realize it but earlier on I had accidentally bumped the neck of the violin on the metal edge of the music stand right across the strings.  The moment it happened I was concerned as to whether or not I damaged the violin. Luckily I didn't even put a dent or a scratch in it but I overlooked the fact that the metal edge nicked and cut the silver winding on the D and it was slowly starting to unravel and, as it did the vibrations of the D and the adjacent strings set the loose winding into vibration and created the annoying buzz.  the fix was to replace the string. This could of course happen to the G or A as well.

In any event, I post this as one more thing to consider and check if your violin starts making strange noises that it should not.