music playback problems iOS7 iPhone 4 - music stops restarts or speeds up

I have a iphone 4 with iOS7 (v7.1). I installed iOS7 many months ago and have been playing music just fine with no problems for many months. Over the last two days while listening to music (songs on my phone rather than thru and app like Pandora) for about 15 minutes, the songs would suddenly stop or restart or start skipping or start speeding up. Sometimes they stop 11 to 15 seconds into the song or sometimes stop or skip 3 minutes into the song. This has happened multiple times in differnet partsd of thew day. It seems so random. I have tried different songs, some downloaded, some put onto my computer using a CD. All songs are either AAC or mp3 and the problem is consistent and persistent. Is this a sofware issue, a memeory issue ( have 32 GB phone with 4.4 GB of space reamining) or do I need a new phone?