My iPhone 5s keeps auto deleting texts
I've had a number of issues with my iPhone 5s. It has done something similar to this a few months ago as well but was resolved after doing a hard restart. In any event, lately, it's started to shut off on its own and restart. I couldn't access certain apps. My contacts all disappeared and then reappeared a few days later. It says the storage is full, which it isn't, and taking photos isn't happening. It's recently started automatically deleting all my texts. Like clockwork, every few hours, the texts disappear, whether I've read them or not.
I've done the hard restart several times, to no avail. I'm sure I should take it to an Apple store to see if there's anything they can do. I could get a replacement phone, but don't really have the money to do so.
In any event, has anyone else had this or a similar problem? Everything's up to date. Any tips or suggestions are greatly appreciated!
iPhone 5s, iOS 10.2.1