hi, I believe I may have a problem with my knee or...

hi, I believe I may have a problem with my knee or bones. I started feeling knee pain for a few years, but it keeps getting worse, sometimes at night and sometimes when I am only sitting. It is my right knee it is a dull achey pain, sometimes its a sharp pain sometimes its my inner knee other times it on the outside of my knee, it bothers me a lot my knee gives way a lot i feel like Im about to fall. My back also hurts a lot so do my elbows at times when I am praying as well as my shoulders. my shoulder pain is strange id be sitting down casually and i get a stabbing shoulder pain on my left shoulder more often than my right but it also happens to my right shoulder somemtimes, its so strong it lasts for a few seconds and I cannot lift my arm and then it disappears. My right knee pain is almost constant now but sometimes i feel like pin point pains around my right knee and sometimes around my left. My right knee swells up sometimes. I've been to three doctors (only complaining about my right knee nothing else) one doctor diagnosed me with chondromalacia patella, another doctor said nothing is wrong with me and a third doctor (most recent visit 1 year ago) said i had tendonitis only because an ultra sound showed my knee tendon connecting my knee and my femur to appear thicker than normal. Please help guide me as this is bothering me, I am a 23 year old female with a healthy lifestyle im not super athletic but i work out when I can my weight is 54 kg my height is 156.