H1B Amendment

Hi Guys,

I was working for a X company in New jersey, my H1 got picked and approved, my contract was over and joined Y company in August before the start of my H1, i was still in my OPT when i joined company Y. My employer didnt file an Amendment yet.

Do i have to file an Amendment ?

Its already been 4 months working in Company Y is it possible to file Amendment now, will there e any issues ?

Please Help,

Thanks in Advance.