Thanks for placing your query here.
I can appreciate your concerns.
In his case the tummy pain is not likely due to zyrtec
which he was using since april beginning.
If it was due to pulmicort
it should have gone within 72 hrs of stopping pulmicort.
By 72 hrs only traces of these medicines remain in system.
In your case there may be some other cause of tummy ache so you should take him to your GP.
Hope I have answered your query.
If you have any further questions I will be happy to help.
Wish you good health.