K.K.
Not really a suggestion for daytime, but whenever any of my kids (6 mos, 4yr and 7r) get a cold, I use a Vick's vaporizer (steamy/warm humidifier) in their room at night. REALLY helps them sleep. Awhile back, my daughter had a cold. We had a long night of coughing, and then the next night I put out the vaporizer, and no coughing...slept soundly. Now, anytime one of them gets a cold, I automatically put out the vaporizer. Works everytime. (you do have to close their door almost all the way though...to trap the moisture in. I usually leave the door cracked)I figure it is most important for them to get a good nights sleep. I don't think those cool mist humidifiers they suggest do anything. I have tried that and it made no difference. Good luck, it sounds like you are doing all you can!