Lost contracts, apps won't open.....

Hello everyone,

I have an Iphone 6Plus it is running IOS 10.2.1. It's 16GB and I Have like zero space. everyday I try and free up space... by removing pics and deleting unused apps... deleting imessage conversations. Anyway yesterday I had 0 mb of space which isn't out of the ordinary but I checked my phone this morning and everything was fine. About an hour later I look at it and my contacts are gone... all my imessage convos are gone...every app I try to open won't open... my email accounts are gone... if I get a text message it stays there for a couple minutes and then disappears... i was signed into icloud and everything still wasn't there... It logged out of icloud and now i can't get back in... I put my username and password in an it just loads but nothing happens and then it stops loading... I can't connect to wi-fi either anymore.. if i try to add an email account it won't load my username and password. This whole thing is very strange. I'm wondering if this has happened to anyone else. I am going to get the 7Plus with 128gb of space anyway since my phone just totally went crazy and i have no space anyway. I don't know if this issue has to do with space but I freed up a bunch and it's still going crazy.