Do you know that Syrian rebels claim that they were subjected to chemical weapons attack almost every week?

I am not making this up. If you follow the social media account of Syrian rebels and their media people, they make claims of chemical weapons attack almost weekly (and some times more frequently) and sometimes they say that there were an attack by chemical weapons but only one was killed form it.  Like this one from yesterday: how come this didn't get media attention and how come it did not result in US missile strike? How come?

Asaad Hanna (@AsaadHannaa)

4/7/17, 8:34 AM New chemical attack by chlorine gas on #Harasta and Qaboon eastern #Damascus #Syria