Hi Lindylou
Having a firm diagnosis makes it easier, but if you have information from GP or other medical professional or can show you are currently being tested, there is nothing to stop you from applying and showing how your condition currently impacts your ability to work.
I can't tell you whether or not your should withdraw your claim - only you, with your knowledge, can decide that.
BIS
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
