Ang- I'm no doctor and I've never played one on TV, but the description of the pain you are feeling sounds like the radiating pain I had once when I had a pinched sciatic nerve... I don't doubt the cause for you may have been over doing the return to running too soon after your last marathon (Boston, congrats by the way).
Fo me it was 600mg of ibuprofen three times a day, gentle stretching and a massage... my therapist showed me some stretches to help out. You may try gooogle and see what you can come up with. As for returning to running...I would WAIT TILL THE PAIN IS GONE and then start back jogging really easy for a mile or two for a few days to be sure you don't make it worse. Also, any compensation or pain is just your body telling you to stop before you do something worse.