Hi there, Thanks for writing in. I am a qualified and certified cardiologist and I read your question with diligence. Apparently, you have lone atrial fibrillation for which you have been taking Warfarin an anticoagulant drug. Are you getting your INR (International Normalized Ratio) a test for anti coagulation monitored as had been advised? Because, less dose and excess of dose which can depend on season and food you take can cause problems. Your present problem seems to be related to spine and you ought to get yourself checked by orthopedics specialist who might need a scan or x-ray before starting real treatment. Meanwhile, you will have to seek relief from pain by OTC drugs like Brufen and Tylenol. There is remote possibility of it being related to irregular heart beat and less anti coagulation that an embolus has lodged in one of the smaller arteries of leg. The point against that is then pain will not involve thigh and if it has affected larger artery to affect thigh then you would have been much much sicker for the blood supply of whole limb would have been compromised. Therefore, I feel it is neurological pain, with aging, degenerative changes in spine sets in and it tends to press the nerve causing the kind of symptoms you have described. I hope that answers your question. Good Luck. Best Wishes. Dr Anil Grover