Strategies for those rough days

Being unwell can be very isolating. I lost my much loved job and now work part time from home. I hate  it but can't get anything else. I went to an interview last week and completely lost the plot half way through--I must have sounded like a complete fruit cake. It was absolutely mortifying.
My brain doesn't work and simple problems become major issues. How do we get through this? I have no idea.