My baby

Today was Zach's weigh in for the week...last week he lost a half a pound, and this week he lost another 4 oz so that is almost a pound in 2 weeks. I am so frustrated with all of this, my baby can't keep weight on, he can't eat food, he can't be a normal 19 month old baby. It feels like we are just fighting a neverending battle and we keep losing. We are supposed to keep doing food trials but every food we try he gets diarrhea for a week and loses the little bit of weight we just got him to gain.
It is so difficult fighting this because on the outside he looks and acts normal. He is happy playing and running but his problems are on the inside and sometimes it's hard to explain that he is really sick when he doesn't look sick. But believe me, when you have to change dirty diapers with diarrhea all day and hold down your baby when you clean him because his bottom is so raw  and stay up all night listening to him screaming because his stomach hurts you realize he is sick and food is making him sick.
I try to imagine a life with no food, our daily life is so revolved around food. I try to imagine his birthday's and holidays and sending him to school and it breaks my heart that he can't have normalcy in any of those events. With Halloween coming up, we have been trying to plan how we can let both boys dress up and go trick or treating but have to convince Zach that he is cannot eat anything he gets.
I try not to complain about my sons' illness because it is not worse, I could not imagine having to go through a child with cancer or worse but lately it just feels like my son is not getting better and nobody understands how hard his life is or what it would be like to live in his shoes.