Thanks for all the information! I have indeed been tested for D and B12, and I eat nuts and yogurt and take Mg supplements. And I was tested for vascular problems (none found). I should also have mentioned that the swelling pretty much stopped after about a month of keeping my feet elevated, but the neuropathic pain and cramps that arrived at the same time didn't stop--they got worse. So i guess the swelling is now a non-issue, except that I think it's odd that it seemed to bring on PN and then departed, leaving its trash (the PN) behind it. :-(