I think the fact that your need does not hurt is a good sign. Almost always, when you damage a knee playing sports, there is pain afterwards. This pain comes from stretched or otherwise inflamed ligaments and connective tissue. It is generally reasonable to assume that, if you don't have any pain, then you probably haven't caused any significant damage to these tissues.
There are some caveats, however. It is technically possible, although unlikely, to cause isolated damage to some structures in the knee without having a lot of swelling or pain. Therefore, you should be on the lookout for additional symptoms. In particular if the knee feels "weak" or feelings like it is "giving out" you should seek medical attention. Furthermore if you have a grinding sensation or a "catch" in the knee when you flex it you should seek medical attention.
Your primary care doctor
should take a quick look at the knee. He or she will look for any evidence of tenderness or inflammation as well as any evidence of joint instability. If they find anything, they will likely want to do additional testing or referral, including potentially a visit with a sports medicine or orthopedic doctor.