hi my son is 4.5 months he has difficulty to breath , very fussy, unsettled, has loss of appetite ,and has a bowl problem for the past week or so ( 3 days he had no bowl movements i think he was constipated and suddenly he had dairrhea example i changed his nappy 6 times today and it was all runny and dark green) we had a home visit from a doctor who said that my son has clear lungs no ear infection or throut infection but he may have URI, he didn t give me anything for it he also said my son has a weak muscles in the lower respiraory system . i want your advice do you think he has URI? what causes it? how can we treat it? and how cani help my baby s muscle get better and stronger?