My kitten hurt his tail. Should I take him to the vet right away, or can it wait?

Dear Most Esteemed and Knowledgeable Kitties:
I would never put money in front of my animal’s health, but I don’t want to overreact and rush to the ER just because I’ve never had this happen to a cat before.
My kitten is 3 months old. He jumped up onto the couch and was acting very strange. I [...]