All Achievements gone

My horses have gotten realy slow and I have to bust a block two to three times before it will go away, then achievements that I already have got start poping up, so I checked and they were all gone except the ones that poped up again. then I discovered that I was on a ver. 1.7.5. Is this the norm. with every version you start?
Im new to the computer ver. of minecraft (come from Xbox & PS3 versions).

Truly like the game, just trying to learn. Thank You.