Diagnosed with PFPS but not sure if it’s right

I’ve had knee pain for about two years, that’s has been a lot worse this year to the point I can’t walk properly without support (either a support band on a good day, or a cane on a bad).

I’m 22, female, relatively inactive (but work an active job in hospitality). The pain affects one knee (the right), and my doctor said I don’t have a lot of strength, and that my knee is stiff. The thing is that the strength issue is likely because when we did the physio, I was in pain and didn’t want to worsen it (physio has not been helping me), and the stiffness is something I’ve been struggling with in general.

There’s also a lump in the bottom right side of my knee. It’s not solid, like I can press on it, but it is hard. I know the doctor felt it yesterday because he checked it against my left leg to make sure it wasn’t just my anatomy (it’s not), but didn’t say much, except asking me if I have a history of cancer and then referring me to a different hospital. They’re still going ahead with the PFPS diagnosis though, and haven’t x-rayed me or scanned me or anything and I’m slightly worried about it. It seems ominous that he’d ask me about cancer after feeling that weird lump, and then not do anything else.

I’ve been passed through 5 different doctors for this now and I’m getting fed up. Every time, they squeeze my knee, make a new referral and then I have to wait just to be squeezed again. Any advice on what to do?