Can motrin and Aleve (naproxen) be taken together for tooth pain my 13 yr old has severe pain and needs a root canal but motrin alone doesn't seem to be working

No. I would recommend alternating between otc Motrin and tylenol (acetaminophen) every 3-4 hours for short term pain relief. See the dentist as soon as possible for definitive treatment of the tooth in question. Definitive treatment is root canal or extraction.
RCT instead. Especially for a 13 year old, i would rather your child be seen by a dentist immediately to start the root canal therapy rather than waiting and trying to load him\her up on pain medication, which may not even work sufficiently. You should try to find a dentist to at least treat him\her on an emergency basis just to get him\her out of pain.
No. They're in the same class of medications (nsaids) so the toxicity is additive. You can take tylenol (acetaminophen) with motrin.
See Dentist. No. Both NSAID. Dose may be toxic. See dentist ASAP for definitive treatment.
No. You cannot take 2 nsaids together. You need to see a dentist asap.
Seek out a dentist. Over use of Motrin and aleve (naproxen) can cause permanent liver damage. What your 13 year old needs asap is to see a dental professional. I would think there is an emergency 24 hour dental center somewhere in san diego where you could get the appropriate care started and the right medication. Root canal treatment is not really painful and your 13 year old tooth's will be saved for a lifetime of use!