Leukotrienes are the twilight zone of pharmacology. I will try to explain later. It has to do with cause and effect going in a circle.
The only way out of this circle is time. Your best bet is to take the very best care and wait.
Personally, I wouldn't assume that Singulair is to blame for everything. If your child has been off Singulair for that long and you feel that there may be an unrelated problem, don't ignore it. Consider carefully what he is eating, etc.
stomach best bet twilight zone cause and effect pharmacology unrelated problem singulair