iphone 5 volume low

Hi my iphone 5 volume is really low. It started yesterday i recieved call and the ringtone was low. The volume is on the highest but still ringer, texts, music player, speaker phone calls etc is low about 20 % of what it should be. Software is all up to date, ive reset etc and its still the same. Phone about 4 mnths old. Any help please appreciated.