Rotovirus symptoms and conditions

My 4 year old Son has had diarrhea from about the last 4 weeks... we have started some tests for Celiac disease but today it only occurred to me today that he has been on Singulair for about that time frame... after all the worry and reading these other storied Im even more convinced that it maybe the Singulair..
Im just hoping that someone might read this sometime today or the next couple of days to tell me if when they come off the singulair how long did it take for the diarrhea to pass. My son had is last tablet 2 nights ago ( so he has only been off it so far for one night. But he still has the diarrhea.. should it have started to come out of his system already.

I have some more questions for you guys. I am looking for connections to the killer t-cells that appeared in asthma cases. I would like to know if your child was vaccinated for hepatitis B, at what ages, and if you child has asthma. Also if your child was one of the ones vaccinated for rotavirus.

Thanks in advance.