I would recommend doing a force reset. To force reset your Apple watch- Hold in the crown and side button until you see the Apple logo pop up on your screen, it will reset the watch from there. Some other things you can try is- Cleaning in and around the crown using water and a small brush if you have one for any dust or debris that could be interfering with the Apple watch's crown, also try updating your Apple watch to the newest update. If none of these work, then this might be a hardware issue that you will have to contact Apple support directly about to get it looked at and repaired.