Hello,
Since the x-ray turned out to be normal you need not have to worry much. Because there won't be any bony Injury.
Usually this symptoms might have caused due to either of the reasons.
Ligament injury or the
muscle weakness.
Since it's bothering you from 6 months I think you should opt for an MRI.
Usually any ignored
knee injury in later stages develops major issues, so it's better to he cautious.
Also, the pain you mentioned is behind the
patella, I will advise you to do water fermentation and then static
hamstring and static Quadriceps as the form of exercises.
Which should help the knee muscles to have enough strength to avoid the knee cap bone to rub against the thigh bone and thereby relieving the inflammation.
Wait and see with the exercise if all goes well than MRI might not be needed. But it fails then we need to take an MRI for precise exercise prescription.
Hope I have answered your query. Let me know if I can assist you further.
Take care
Regards,
Jay Indravadan Patel, Physical Therapist or Physiotherapist