My son is the same as your son. I think that your maid use her strongly eye to look at your son. That's why your son always cry. Before I faced the same case, my maid looked at my son very strong when I'm not at home or I didn't pay more attention on her even I stay at home. But, I fried her already. Anyway, Take Care!
My son is 20 months now, but he can't speak as well. The same as your son. Actually you can keep an eye on your maid from now on (but don't let her discover you look at her), when she carry your son or play with your son ... etc.
I think you better install an "eye" because when you went out just a few min., your maid can do everything to your son even you are at home.
So, you install an "eye" at home you just know what matter going on. You can 安心 more, no need to 估估下, try it!!