Mri is unnecessary diagnostic method(my doctor thinks)i have dg:discopathy l5-s1,and severe sciatica,and i don't react well on ph therapy,what to do?

Doctor is wrong: Your doctor is wrong. At age 30 and with your symptoms, an MRI is essential to establish an exact cause and help determine treatment options.

See Pain Doctor: Employing a multi-modal approach, most fellowship trained pain specialists offer the most effective management of painful conditions. To accurately diagnose and treat patients, we will utilize imaging studies, electro-diagnostic evaluations, history ; physical examinations, targeted physical therapy, appropriate and responsible medication management and cutting-edge interventional procedures.