I hope I am wrong, but there is a chance you have a fake phone.
If you search the threads you will find that other members whose phones were fake had similar issues with google play store after updating their ascend p6.
Maybe you should try install cpu-z or another program that will show you the specs. If you find this
(check posts #15 & #16, hardware mt6589) then your phone is fake and you should probably contact the seller...
EDIT: I just show that you are the OP of this
thread, so I am probably wrong.