Small intestines symptoms and conditions

Hi. My eight year old daughter has been on singular for 6 months. She has had chronic stomach pains that she says feel like pressure. Her appetite is terrible. She always says she isn't hungry. I have to search for anything I think she will eat. She is very tall and very thin for her age. She grew an inch in the last year but gained no weight. First time her growth just stopped. No surprise as she doesn't want to eat. I took her to the doc several times and they think she has acid reflux and have given her 2 different acid eliminators ( which freak me out as well) Said she should see a gastroenterologist. We have appointment in March . I started reading this site and thought well maybe it's the singular. So I called her allergist and told them I was taking her off to see if that's why she has the stomach problems. They said I could since it wasn't a big trigger time(seasonal) and she wasn't sick with any cold or flu) She gets mild asthma when sick. Her allergist asthma doc thinks her stomach aches are related to the mucus dripping into her stomach. I have taken her off all meds to try to see if it could be the Singular. She also has been very tired and can't keep up in her dance classes. Her school teacher had to put her in the front of the class because she said she wasn't paying attention. She seems to lose it over anything that requires focus or attention.She also seems kind of depressed. She is worried that something is really wrong with her. This child used to eat normally and is gifted academically .Her tests results(taken while on the Singulair) went way down from last year. She was put in gifted pull out program from last year results but would have barley made it in this year based on her much lower scores. That does not make sense to me. Never has had attention or focus problems before. I will keep everyone posted. Does anyone know how long it might take to get this drug out of her system? Has anyone else had this kind of reaction to this drug? I also wonder whether she had reflux before but this made it worse? I had her blood tested for Celiac and general stuff and nothing showed up.I wanted to get the Singular out of her system before we see the G.I. doctor. anyway thanks, Elizabeth