hi my 14 year old boy,had runny nose,weezing,blocked nose,drewling,watery eyes and this barking cough.took him to a doctor gave med s and antibiotics,it s day three all the other symptoms are gone now he lost a lot of weight,has diarrhea and seems very week.what could be the cause. he refuses food and formula occasionaly.gave him rehydrate just to boos his energy level am not sure it s working though.should i be concerned