1. The kinds of difficulties your son is experiencing
2. Exactly what the test results were in the past, including the names of tests given
3. What interventions have already been tried
If your child was tested by your local school district and no difficulties were uncovered that would merit services for him, it may be time to take him for an outside, independent evaluation that might be more comprehensive.
I would call the toll-free number of the Learning Disabilities Association of America at 1-888-300-6710 to see if there is a branch of this advocacy group within your community. If there is, call them and ask for a referral for a full psychoeducational evaluation as well as information about whether you might get funding from your school district to have it done. You can also get referrals from the National Center for Learning Disabilities (1-800-575-7373) or the International Dyslexia Association (1-800-ABCD123). Smart Kids with Learning Disabilities is also an interesting website for parents that has many ideas for supports you or your school could provide.