I Have Been Having Anxiety Panic Attacks And I Have

I have been having anxiety panic attacks and I have just asked for 12 months leave from my job without pay but I have been advised that I need to tell them the reason why I request the leave. My Dr has put me on a MH plan to see a phycologist but I haven't been able to afford this, this month. Just wondering what the best way to request this leave without telling them too much because it is embarrassing.