Lower back pain mri. Simce last 15 days?

I am from IIT patna and preparing for upsc and i study for 10-12 hours a day. I had low vit d (7.5) in sept for which i had calcirol powder every week and calcimax 500. Then I had knee pain, lower back pain radiating in left hand as well as leg muscles in the begining of December and then i noticed my left lower part thigh to be thinner than right and also i had problem in squatting or when sudden load applied on left knee. Xray report of spine was loss of lumbar lordosis due to muscle spasm and mri report was L45 mild disc bulge abutting thecal sac. My orthopedic doc says my reports are normal and asked my to go for knee mri but another general physician said that it's due to disc bulge. What could be the problem here please help me as i have missed my studies simce last 15 days?