I have felt like this a lot of times....And at these times, the only thing that stops me from believing I'm useless is the factual evidence that I HAVE managed in the past. So, do keep that in mind at all times and don't hate yourself because this isn't you

Maybe focus on the basics, give yourself more resting 'comfort zone' time, and tackle one thing at the time...And maybe talk to your T about it?
Although, not knowing what will happen with benefits after the next 2 months would probably stress anyone out...

Anyway, please don't freak out about freaking out!
I hope you feel better soon