An MRI is safe but not necessary unless you have serious symptoms beyond those common to a concussion. Concussion symptoms can easily last 6 months or longer. The intensity of the concussion plus how you have responded to the concussion can determine how long the symptoms last. Most doctors do not give much help with instructions for recovery.

What have you been doing to help with recovery ?

I just saw you post about the physiotherapy and your exercises. It sounds like the physiotherapy may be making your condition worse. If you have an upper neck injury, it needs gentle therapy and careful posture. Many physiotherapists get too focused on range of motion and such.

The MRI should include imaging of your upper neck with your head turned sharply to each side. This may show any upper neck injuries that need to be considered.

Does your physiotherapist tell you to ice your neck and back of your head after therapy ?