All music randomly deleted and no space?

I have an iPhone 4S running 8.1.2 and my music was somehow randomly deleted. All 400 plus songs just disappeared. My music took up most of the space on my 16gb phone and now apparently I have barely any space left. I was told I had 0mb left and ran iCleaner and it only deleted 300mb. Now 4ish days later I only have 100 left. Anybody with a solution or reasoning behind my deleted music and the random space being taken up, please let me know. Thanks!