First of all, sorry for the late response. To me these type of complaints seem to be anterior knee pain, most likely to be incurred by the knee cap. Do you remember whether these painful nights follow day in which you were more active or more sitting on your knees, having them flexed? The knee cap is particularly at your age vulnerable to long standing compression, which induces a sore spot there. You could compare it to a bruise. It is nothing to be afraid of and it will disappear in time. Although it could last for several years. If it occurs again, just try to move your knee a little, take some painkillers and go on living, for it is not harmful, it just hurts.
I hope you appreciate my answer.
Hope this helps.
To your musculoskeletal health,
Your presentation is not very clear, so the answer to your question will not be clear. What you need is an assessment by an orthopedic surgeon specializing in knee problems. It sounds like your kneecap, or patella, is the source of the pain. However, if I were your doctor I would need some additional details in your history about what part of your knee hurts and whether there are any other associated symptoms. I would need to perform a detailed physical exam. I would also want to personally review your X-rays, and if they are normal then order an MRI to look at the soft tissue parts of the knee (cartilage, meniscus, ligaments, tendons, etc.).
Kenneth R. Brooks, M.D.
Osteoid Osteoma a benign tumor is a possibility .
It could be other things, but that's a very common problem.