May I take an advil pm if I have a concussion

If you have a concussion you would have been to the doctor, given medication and/or instructions, I would be wrong for us to give advice, that may or may not follow your doctors.

Plus we have no idea what medication you doctor gave you for this.

I second what Chuck said.

Obviously you went to a doctor if you know for a fact that you have a concussion. You should follow whatever orders the doctor gave you. If you're concerned, or have questions, you should call the physician that treated you for the concussion.