What happens next i am still employed my doctor gave me six months off work DWP say i am fit What Next?
You don't say if your claim was for Incapacity Benefit or ESA, but in any event as you and indeed your GP disagree with the adverse decision, you will need to lodge an appeal.
The procedure for making an appeal is detailed on this page HERE.
Nothing on this board constitutes legal advice - always consult a professional about specific problems