Here in headline you have ask for treatment for
swollen knee pain. And in your explaination you have mention many other issues like headache and
sinus problem too.
You have mention patient have taken many medications but I suggest when
MRI showing every thing normal for head and if it is only sinus. Then for that you can give him multi vitamin and multi mineral supplimaent from natural source along with some exclusive vitamine c suppliment. And also ask him to do
yoga and paranayama regularly for some more relief.
For sinus if it does not work then visit a good ent doctor for further examination and treatment.
For knee pain again if MRI is normal and there is no history of trauma then it can be knee cap
movement disorder. I suggest to visit a good ortho and physio for further examination and treatment.
Here in physio they will also help with different exercises which will help to correct the biomechanics of knee joint. As well electro therapy along with heating will help for some more pain relief.
You can also use on your own
cold pack at home to reduce inflammation and swelling.
Follow all above steps and I am sure it will be helpful.
Take care.