worried about weight

My son is nearly 4 he has always been smaller than other children his age (myself & his father are not very tall)  when he was a baby he would vomit a lot of his feed up, this continued until he was about 10 months old, when on solids he would cough and then vomit.  then over the last few years he has been doing it on and off, it will continue for about a week or two randomly then stop. If he cries to much then he will vomit.  he was diagnosed with HSP just after christmas, but is now well in himself,  but recently he has been refusing to eat and then when we tell him he has to he is sick, then after says he is hungry and then has something to eat with no problems.  I do not think this is related to the HSP as it has been a problem for a few years, when I took him to the doctor last year they just said he had a virus.  this has been happending for a week now when he randomly vomits.  My main concern is that I checked his weight against the growth chart and he is under the 0.4th line weighing 26.8lbs and waring 1-1.5yr trousers, which fall down.    He always says his belly hurts when we are having a meal, we asume it is because he doesnt want to eat & then he is sick.

Can you give some advice, we are very worried about his weight

[Kevin Kennedy, Ph.D.]

In light of your son's history and ongoing problem I would suggest an evaluation by a pediatric gastroenterologist. Ask his pediatrician for such a referral. Yes, his weight is a concern, but I am more concerned about the ongoing GI discomfort and vomiting.