ladyofthelake,
There are several things that you could have injured in that area.
You may have sustained a bone bruise of the proximal part of the tibia. This would show up on MRI, but there is no treatment for it except time.
You may have set up some inflammation in one of the bursae around the lower part of the knee, causing a bursitis.
You could have injured the fat pad, which is located under the patellar tendon. Again, this would show up on an MRI, but there is no real treatment for it.
However, if the area is just not getting any better, you may want to see an orthopedic surgeon for a thorough evaluation.
Good luck.