Help please!

I feel as if I have taken several steps backward the past few days. The beginning of last week I was doing really well with my PT, not overdoing and not in pain. After PT on Tuesday, I decided to visit the gym for the first time since the end of April, when I really started having tremendous pain which led me to the RTKR in June.
I tried to do just 5 minutes on the recumbent bike, the same five minutes I did yesterday at PT and was feeling a lot of discomfort. The bike seat wasn't any closer, but the angle seemed to be a bit different, so I stopped at 2 minutes. Whenever I use the bike, when I push the pedal around and over, I am starting to get the exact same pain I felt when I stood up 2 weeks ago without my cane. The pain is intense, quick like a knife on the inside of my knee in the front. There is still swelling there no matter how much I ice and elevate. The pain also happens as I apply pressure on the ball of my foot and push off if I am tired or have been on my feet for more than about 10 or 15 minutes.
Anyway, I stopped using the bike and moved to do leg presses. The plates/weights are definitely not the same as the machine in PT, so I just used it at 10 as I didn't want to overdo. No pain with this machine as I am flat footed when I press instead of rolling off of the ball of my foot. I did some upper body exercises and again tried the bike, which still hurt, so I stopped an went home. That was it for me for the day, I did not really do anything else after driving home except put my feet up, ice and rest. I was feeling the pain in that part of my knee for the rest of the day and all night.
The next day I returned to PT, feeling somewhat better and again tried the bike with the same results. Every time I push the pedal over, the intense pain returns, once I am off the ball of my foot, the pain in my knee subsides. I competed the five minutes going as SLOWLY as I possibly could, to limit the revolutions. My PT thinks I might have bursitis there? I really don't know what that is or what to do to help it. I completed a few other exercises (one for getting the last degree or two in my extension, leg presses and I practiced walking up a small step with my new knee. I could not walk down so we just walked up one step the 'regular' way with my cane and holding on to a piece of equipment and walked back down it the way I have been doing it since the TKR (bad leg first with cane, holding on).
By the time I hit Friday and had PT for my third time, I was in so much pain, I did no bike, had to stop every other exercise about 1/3 of the way through; this thing on my knee is killing me again. What is happening to me? When the PT and I looked at the area, you could literally see it throbbing. I left after about 25 minutes, feeling defeated and in more pain.
I have done nothing all weekend; I dialed everything back to what i was doing the first week I came home. I don't have PT again until Tuesday and I have not been back to the gym since last Wednesday(the only time I went). I am at a loss as to what to do now. Even when I am icing and elevating (l have been doing it all weekend), the darn thing is giving me these stabbing pains and I am not applying ANY pressure through my foot or even standing and walking. The other thing I notice is that area, no matter how much I ice, doesn't get as cold as any other area. I can ice for 45 minutes and it's still warm there.
The area is still swollen and the shooting pain jumps up to about a 7 every time it happens. I am still taking all of my same meds and have even increased the amount of Tramadol so I am now taking it 4 times a day ( I was down to just two times) with my 1,000 mg of Tylenol. I am even taking some ibuprofen too as I don't know what else to do.