My world stops working

I don't know how to describe this other than I hop into my world I've been working on for a few weeks now and since last night I can only walk a few steps and then the game stops working. By stops working here is what I mean. I can open a chest but then the chest stays open and I can't interact with it again. The world stops loading past a few chunks and I can't break things exactly... They break but like sand doesn't fall if I break sand under it and I don't get the sand blocks the block just disappears. Also, the game gets hung on the saving game screen, I let it go for 10 minutes with no results. I've tried copying the world and the same error occurs, but when I start a new game with the same seed it works fine. I can play on realms just fine, so what's wrong with the world I've been building?

I'm only running with the "natural" resource pack.