Theres no such thing as a crazy patient, just an incompetent doctor!!!!!!
I've had 14 knee surgeries including replacements. You'd be amazed how many orthos don't think women are capable of injuring their knees the way men do. I walked around for 2 years on a totally messed up knee as a teenager(late '60's)because the prevailing theory was that only professional women athletes could tear the cartilage and ligaments in their knees. WRONG! In fact, they now know that women can injure their knees more easily than men because our hips are wider, especially during pregnancy and after childbirth. It changes our center of gravity(as we all know)and our ligaments are more relaxed for delivery.
So either see another ortho or see a rheumatologist(medical side or orthopedics). If the pain occured after you "whacked it", it could be a bone bruise or even bursitis. Bursitis hurts like hell but other than pain, doesn't do anything bad to your knee. But get it checked out either way.
Jenny