Google mobile data usage

In the last 2 months, my wife's data usage has ballooned for no clear reason, since her mobile habits and phone have not changed. In this billing cycle with a few days to go, the phone's mobile data usage utility shows what it states is "Google" used 3.12 gb out of a total of 4.06 gb. Everything else--Maps, Facebook, Spotify et al are distantly behind (nothing more than 0.24 gb). Background data usage is on and she will turn it off, following advice in other posts. 1. Is there any way of finding out what in Google is using all this mobile data? 2. Any recommendations on apps that can get more specific about what is using the data? Thanks for any help. David