My 12 year old boy gets daily headaches(6months) they are around his right temple only, last from 20-40 mins, resolve on their own, no medication. no other symptoms. he is thriving otherwise. i'm concerned its a tumor? could it be stress or anxiety?

Low odds. Some worrisome symptoms and signs of brain tumor: recurring headache in mornings, unstable gait, disruption in coordination, motor weakness, cranial nerve palsy, and seizure. Careful neurological exam should be the first step. I would recommend him to be examined by his PCP.

Unlikely to be a tumor; certainly could be from stress/anxiety, as this is the most common cause for headaches in this age group. It would be best to have him examined by his regular doctor and if all is normal, also address how to handle the anxiety/stress. Also, keep a log of the headaches and any other symptoms, when they are, foods eaten; this will also help the doctor to diagnose the cause.