The environmental allergies your child has are very common; there is also a LOT you can do to minimize his exposure to those triggers in his environment. Removing carpets as already mentioned is a big one; putting protective covers on mattresses and pillows (look for ones rated for dust mites) and using washable curtains, frequently washing bedding in hot water will help there. Air purifiers using a combination of hepa + charcoal filters are very good for removing pollens, dust, dust mites, animal dander etc from the air. If you have a pet that you cannot part with, at the least keep it out of his room. I'd also consider talking to the dr about trying a daily nasal spray for the inflammation & congestion the allergies cause. We also have good success using the saline sinus rinses.