Removing dairy and gluten pretty much put a stop to my allergies. I also had IBS issues that stopped after going paleo. Just like you I used to always get sinus infections, constantly sick and went so far as to get immuno-therapy shots for my allergies to no avail. The only thing that worked was going paleo and sleeping better.
"If man made it, don't eat it" - Jack Lallane
People say I am on a "crazy" diet. What is so crazy about eating veggies, fruits, seafood and organ meats? Just because I don't eat whole wheat and processed food doesn't make my diet "crazy". Maybe everyone else with a SAD are the "crazy" ones for putting that junk in their system.