What Causes Severe Joint Pain In Knees?

I am 42, 5ft1, 9st3. joint pain since last year, had carpal tunnel surgery end of last year, slight improvement but hands and knees very painfull mornings and after sitting down. I need to know why it is taking so long for diagnosis and what I should ask my consultant tomorrow. Getting an ultrasound scan on hands tomorrow and going to ask for knee scan. Am on Naproxen 500mg twice daily and omeprazole