"I've been told it's a baker's cyst" by the doc? My Mom had one years ago, but it was deep in the tissue and we couldn't feel it - they found it with ultrasound.
Seems an unlikely location for a bone spur, but I suppose it is possible, or it could be referred pain from a spur elsewhere. I get shoulder pain at times from a big spur in my elbow.
The swelling is more likely from a cyst than an spur. You could try lying with your legs up the wall to drain the fluid back to your abdomen, when it can be absorbed and excreted. Massaging the leg with a firm stroking motion can from ankle to above the knee while it is elevated can speed the process. Also, have you tried keeping the leg elevated when you are sitting?
Just a few ideas.
Sue