I suffer from depression so I go through that a LOT. Some days are just sofa days.
I do have a "sun therapy" light. It really helps when there are gray days with no sun.
Getting out of the house helps.
Spending time with people helps.
And surfing quilting blogs helps.
So, if the blues continue too long, see a doctor. Otherwise, this too shall pass. And when you do get going again - look out. There's a lot of creativity to make up for!