7 mo old coughs&strains often daily since 4 mo,x-ray neg,ped says possible allergies,seems better when ac is on, why? suggestion 2 help? concerned.

Your doctor is right: Follow his/her advice, if your pediatrician wants to refer you to an allergist, better go, meanwhile make sure that the environment is controlled, viz. no Smokers,pets, stuffed toys, feather pillows, indoor plants, or wall-to-wall carpet, as much as you can, your baby feels better when the AC is on because it is the best dehumidifier, allergy symptoms usually flare with increased humidity, good luck

Sounds environmental: The first months are troubled by narrow nasal passages & exposure to dust, fragrences, smoke & other irritants.Baby tries to flush these out of the nose with mucous but this often ends as congestion & produces cough & rattling with breathing. The best rx is washing out the nose with saline & suctioning the remainder. Eliminate irritants from babies environment & this will happen less.