Audio book playback skipping forward

Suddenly I can't play Audible (or audiobooks in Apple Books) on my iphone in the car. Rgardless of the book, any movement, any slight knock on the phone and it skips forward 30 seconds. I get through around 15 books a month, and a lot of my listening is in the car. Now that's become impossible. Ive deleted and reinstalled the app multiple times. Ive deleted every downloaded book (hundreds of them) and then tried downloading just a few. Ive gone into my iphone settings and adjusted everything in the accessibility that suggests anything to do with 'vibration' or 'shake'. Ive even done a complete factory reset on the phone. Absolutely no change. On my ipads however, no problem at all. If I sit at my desk and put the phone down on the table whilst its playing... it jumps forward. If I move the phone from one hand to another, it jumps forward What has happened in the settings on my phone to make the books jump forward in this way. Any help gratefully received