A few weeks ago the back of my Iphone4S cracked so I bought a new one on Amazon. I know how easy it is to replace the back of the iphone so when it came in the mail I replaced it. Recently while on my iphone I will try to go into apps and they will just shut out immediately after clicking on them, and when sending a text message the message will not fully send. So I put the old cracked back on and it seems to be working fine again. My question is, was it the new back of my phone that was doing this? And when buying a new back is there a specific one I need to buy. I don't want to invest a lot into something that isn't going to work. Please answer…