If you don't ask,who will?
Be prepared for a long fight to get disabilty pay though. Like as much as two years.
Make it clear to your doctor that you've come to the end of your rope and you need to stop working to recover. Once the doctor accepts that the appropriate steps will be taken. You need income if you're sick and cannot work. Mental rest will help your condition. One of the side effects of GAD might be that you cannot muster the resolve to be sufficiently emphatic and demonstrative with your doctor.
If that's the case, print off this message and show it to your doctor, saying: "that's how I am".
Take care of yourself whatever it takes.
You would have to discuss it with him. Sometimes anxiety problems can get worse when people are not at work and don't have things to occupy their minds.