HI, my H1B transferred and I797 and LCA got approved but due to location change, new LCA approved but H1B amendment was not submitted. now as last date has passed, what is the option i have. I have Stamped till JUN 2016 and petition approved till OCT 2016. please advise.

1: Can i change my employer in this case?
2: Should i need to be out of US?
3: what will be the impact of this on my H1B status.