Alright, so above what you have mentioned, the root cause of your problem is the limitation of your internal storage. 8Gb is not enough to keep everything in your device updated including Google service i.e. Google Playstore, Google maps, Gmail, Music, etc. maybe you need at least 12Gb for to keep all that staff updated. So I would suggest to replace your device with a higher storage capacity so that you won't have that similar issues again.