Hopefully the balance issues will resolve as the Claritin leaves his system. For the allergies, I recommend you see a good Pediatric chiropractor. We have one in the Westminster area if you need a referral. My daughter had bad seasonal allergies that caused her to cough, have a runny nose, be unable to sleep, etc. for about 4 months every spring and about 4 months ever fall. It was miserable! She was on steroid inhalers and prescription allergy meds.
A friend recommended a pediatric chiropractor. We took her a couple of times and that resolved all the allergies. Now, if the allergies begin, we take her for an adjustment and that immediately takes care of it. If it lingers a few days, the chiropractor gave us a homeopathic allergy remedy that has worked great for my kids and without side effects.
Good luck, and let me know if you need a referral!
M.