Can overweight cause pain in ankle n lower leg while weightbearing post 11 mnths of severe ankle sprain?weightbearing activity of 10 minutes causes pain

Yes and no: Being overweight can potentially cause increased symptoms in any abnormality of a weight bearing extremity. But if you were overweight before you had your injury and did not have problems, it suggests that your injury may have been more than a simple ankle sprain. There must still be something else going on. Consider being thoroughly rechecked. An MRI or ct may be needed.

It is possible: Are you using an ankle brace? If not i would recommend it. You may also want to follow up with your doctor to make sure any injury has not worsened.