Hi Deborah,
I think that you'll be happy to find that Disney World is AMAZING for Guests with many types of special needs.
You shouldn't have a problem bringing your son's medications and supplies into the parks. Just make sure the medications are in their original containers showing they are prescribed for your son. There are
First Aid Stations at all of the parks that can store any medications that need to be refrigerated or assist you with any medical needs. Some guests bring their own coolers with the medications stored inside and they will hold the coolers for you.
You can also visit Guest Relations when you enter the theme parks if you need some assistance that they unable to provide you at the First Aid Stations.
Keep in mind that it will be really hot in August so make sure you keep your son well hydrated and as cool as possible. If you need some suggestions on how to do this, let me know - I am super happy to assist you.
If you need help at any time in the parks and feel you can't make it back to the First Aid Station, don't hesitate to ask the nearest Cast Member - they will all assist you in any way possible.
Wishing you many magical memories :-) Allison