Sciatica for 3 mths, tingling in my legs and feet numbness in my big toe and achy hips for the past week. mri showed nothing wrong? whats wrong?

Unlnown yet: Mri missed the problem although rare it is possible it missed the problem or was underread, ct myeleogram is a more sensitive but invasive test, L5 root can be pinched in areas hard to see on any study like far out syndrome and far lateral disc herniation can be tough to see on MRI the nerve pinching can be in your buttocks and not in spine at all piriformis syndromekeep looking.

Peripheral nerve : If the MRI does not show a problem at the root level the nerve may be entrapped in the leg itself (called the peripheral nerve).

EMG/NCS: can be very helpful in determining issues that may still be from the spine if MRI is not that conclusive. Also it could be a peripheral nerve injury or neuropathy that could cause his pain and the EMG will be helpful in determining this.