Hi,
Yes,it could be due to the muscle.
As your INR is stable,nothing to worry much as raised INR could lead to
EMBOLISM which eventually leads to
Stroke,
Heart attacks/Myocardial infarctions etc.
From the symptoms,i would like to suggest you to go for
an ultrasound(color doppler) of the limb,
EMG(electromyelography) of the limb,
Sr.electrolytes.
Consult these reports with your physician.
Are you on
warfarin therapy?
Do you smoke?
Are you a diabetic?
Take your medicines regularly,
Avoid any bad habits like
smoking and drinking,
Moderate physical activity in the form of
physiotherapy would be beneficial.
Take careEMG(electromyelography) along with the
Sr.Electrolytes.