hi sara
a bit more info is needed
24hr behaviour of pain
aggravating and relieving factors
examination findings in detail
whether while doing movement is it a through range pain or end range pain
end feel
response to isometrics of knee flexors,extensors,tibial rotators
medial joint pain
causes i suspect from your discription)
medial meniscal tear
medial collateral lig injury
loose body in the knee
pes anserinous strain
anterior knee pain
causes)
ACL injury
patellar lig inj
arthrogenic pain inhibition of quadriceps