Back pain shooting down to knees

Patient: Dear DoctorI am having continuous lower back pain which is shooting down to the knees on the sides. recently i had a full body check up and doctor advised me to check the Thyroid level after 3 months. Recently I checked the Thyroid level and the results were as followsT3 1.23T4 80.76TSH 3.76I feel numbness on my left index finger and dryness.I feel very tired recently after my daily work and back home after a 13KM drive from work place. I do a normal exercise of pranayama daily for about 30 minutes in the morning and yoga of about 30 minutes in the evening about 4-5 days a week. I got a lower back catch during a surya namaskar posture and there it started. the pain did not subside even though I stopped surya namaskar. still the pain is not subsiding. If I stand for some time I get pain on back and knee. Sometime a burning sensation on left lower abdomen too.