I am not a repair man, and I could be wrong but, it sounds to me like something has broken free or moved from it's correct routing location and can/could/will intermittently jam the controls. As easy as it is to open the RC case and inspect for the source of the problem, I would not fly again until that was done. Here is a link to YouTube on disassembly of the Remote Control for another type of repair. Your RC may be a bit different, I could not find a video of a
Phantom 4 Pro controller, but the concept will be similar. Go slow, keep track of your screws, and be very careful around the ribbon cables and electronics. Take as couple of pictures if you think you will forget the replacement order & location of things. After opening it I would gently shake/jiggle it to see if I could locate the issue. I have a feeling it will be easy to determine the problem. I did not watch this video for very long but it looks like a good one. There are others on YouTube if you don't care for this one.