Knee problems

I am experiencing left knee pain. The background and history is as follows: I am 57 yo obese female. No real knee pain until 2 years ago, when I injured my foot, which caused me to walk differently, causing pressure knee. Eventually, with RICE, knee pain went away. About April, the knee pain returned. I went to a family practitioner. He tried cortisone shots. The first seemed to help, but knee still hurt. Another cortisone shot seemed to do nothing. At this point, no xrays or other tests had been done. Fam Prac Dr. sent me to orthopedic specialist (guy who is well known for knee replacement). He xrayed — said I had arthritis (well, yeah, I’m 57 and obese) but said knee surgery not recommended because I had a blood clot 14 years ago. I agreed. He started my on Synvisc. I had three shots, the last was 4 weeks ago. There has been no change for the better, but he said not to call for 8 weeks, as it sometimes takes this long to help. In the meantime, my knee pain has gotten worse. I went back to Family practice doctor for another reason and also, in passing, talked about my knee. Since it hurts in area of front/inner side of knee, he said maybe bursitis in addition to the arthritis. He sent me to physical therapy. I like the physical therapist’s approach- he has started me out very, very slowly and is loathe to add anything if it causes increased pain. But after my last session, 3 days ago, my knee has been much worse – a little more swollen plus last night, there were shooting pains keeping me awake. Normally, it hasn’t hurt that much when lying down. It has also caused my back (lower left side) to hurt.My question is, have I started PT too soon? I know xrays cannot show soft tissue problems — is there another test I should have had?