momma cat had her kittens almost 3 weeks ago. yesterday she moved then & is not eating.she just nurses.?

I had them in a little covered "house". yesterday momma cat started meowing & tried to move the kitties under the bed. I didn't want them under there because I am handicap & if something happened I couldn't get to them. I made up a box & put them at the end of the bed under a chair & a tent of my comforter. momma calmed down. she now isn't eating. all she's doing is nursing.momma comes out every once in awhile to get a good scratch & then goes back to her babies. I feel so sorry for all of them because they are all cramped in the box but that's where she wants to be. is something wrong with the momma?