Common illnesses

i'm a first time mom. my son, stryk, is turning 5 mos this oct 12. a little over a month ago, stryk had colds, which he got from my MIL. he didn't have fever, sleeping comfortably, was eating normal, very cheerful and active despite the cold. so pedia told me to nebulize him with NSS 3x a day and to add 1/2 nebule of 2.5mg ventolin nebule if he's wheezing. the cold quickly went away after a few days of nebulization pero naiwan yung halak. after 1 week i called the pedia and she said to just continue. weather din daw kasi and to remove all possible allergens. after another week, di paren nawala yung halak. since i couldn't get rid of some allergens (i.e. my in-laws' dogs that live inside the house), she gave zyrtec and mucosolvan expectorant and continue neb. both my husband and i have family histories of allergies so i took stryk to a pedia-allergologist in cardinal santos. given the family history, malamang daw hypersensitive lang si stryk and the halak would eventually go away. but to be on the safe side, he conducted a skin test. all results were negative. although stryk isn't showing any signs of discomfort, i'm still bothered kasi ang tagal na nga. first time mom pa ko so shempre wala naman akong alam masyado. has this happened to any of you mothers out there? docs am i getting worried for no reason at all? =(