My volume button keeps lowering by itself.

Basically any time I listen to music or open any tab on any app my volume is going down til it’s completely muted. I recently had my phone die in a very weird way (white and green lines all over my screen) and ever since then my phones been acting up. Currently the volume thing is extra annoying given it won’t do it for ten or so minutes and the physical button will work, then it’s like I’m out of control of my phone. My device won’t rven let me upload the video screen record of the ovcurance. I don’t know if maybe my phone is hacked or something but I need help ASAP.