My 2.5 year old son has been coughing and congested for about 4 days now. Last night, he vomited and it was foamy and whitish green in color. I thought it was induced only from the coughing until he did it three more times today. Once around 3 o clock, again at 8pm and just now (9:25 pm) Is this something to be concerned over? He continues to have coughing fits and sounds very congested, is fever free, has a good appetite, had a bowel movement, but very little urine today.