Three weeks ago i suffered a mild concussion. over the last couple weeks, i have displayed symptoms of post concussive syndrome. safe to air travel?

Yes: Generally speaking it is safe to travel with concussion, although the altitude change may give you a headache. Tylenol should help. Be sure you have seen a doctor and they made sure this is "Post Concussion Syndrome" and not something more serious beforehand. Symptoms lasting past 10-14 days should be consulted by a neurologist and perhaps even a MRI to be sure nothing else is going on.