Death soon as I logged in

I saved my game while I was at home, safe from harm. When I logged into the next day, I was falling and instantly got the You Died screen. Lost everything.

2nd weird death. Finally find a darn swamp and I had all kinds of slime balls. I was swimming above water, hit a wall and got the You Died screen. HOW??? Again lost everything. I managed to get back to the scene of this death before the 5 minutes was up and all of my stuff was gone. I love Minecraft but this is disheartening.