James
If you were previously found Fit for Work then I would expect you to have to provide a medical statement that you have a new condition or that your existing ones have worsened, the DWP will be looking to see whether this would be reasonably likely to result in an award of ESA.
They do have the option of accepting your ESA claim but not putting it into payment until you attend a new assessment, be aware that some of our members have reported waiting nine or months for an appointment.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
