I had a cat get hit by a car and crawl all the way to the back door (up the steps and through the porch) with two broken legs and a crushed pelvis. Eventually she had to be PTS for her injuries, but she didn't complain very much at all. Cat's are tough, when they cry you know something's up- personally, I think you've waited long enough to know whether it's just going to 'go away' or not. Take the kitten in, if you're not okay with spending lots of money then don't opt for the x-rays or expensive procedures. Ask your vet to examine, get something for pain and wrap it up to help the healing process.