We fought with reflux the first 3 years of my sons life.
The reflux specialist we saw told us to use Gaviscon which is a liquid ant-acid you can buy pretty much any place. Just a 1/2 to 1 teaspoon should do the trick when your son is having problems. I used to give it to my son before bed and after meals.
We also put our son on Prilosec. You can have a prescription filled at a pharmacy, they will liquify it.
However, we found it much easier and less costly to buy the Prilosec OTC and crush 1/2 a pill and add it to applesauce, yogurt, ice cream etc. once a day. It takes about 7 days before it will take it's full effect. We used that dose since our son was 18 months and about 20 pounds.
Definatly stay away from orange/pineapple juice or fruit, tomatoe based foods (ketchup), peppers, chocolate, carbonated beverages.
Try these for the constipation: peas, pears, peaches, grapes and raisins all worked really really well for us.
If he is having chronic ear infections get him seen by an ENT specialist, the acid from the reflux can travel up into your son's ears and cause major damage
Good luck and keep me posted.