westie puppy allergies

today i received the test results for my 6 mos. westie puppy. we found some food allergies & i picked up natural balance dog food, which was one that was recommended. my issues are with the few fungi & housedust mites that are involved, also. i looked some of these up, but i am not getting a clear picture, so if anyone has any insight, please respond. these are the fungi: aspergillus, rhizopus, pullaria, nigrospora. i am wondering if having my duct work cleaned out would be beneficial? also, a small portion of my home sits over a crawl space. maybe 12 feet wide by 29 or 30 feet long. the rest of my house is over a regular basement. i vaccuum once per week, dust once per week, use a steamer to clean my non-carpeted floors and i wash his bedding once per week in dye free detergent with no fabric softener. the reason that i am wondering about the crawl space and the duct work is because my previous westie was fine, until we moved here and she then developed allergies (at the age of three). thanks for any comments that anyone might have.