Firstly, I wouldn't allow my mil any alone time with my child if I were you for fear that she'd go behind my back and bring my child to the doctor. That's not her call. Sure, she can voice her concerns... but, unless you're physically abusing your child (or even mentally), she needs to butt out.
Secondly, as many other posters have said, your 2nd child may just not want to talk or have no reason to.
My 2nd child hardly had any words by the time she was 2 yrs old... big time contrast between her and my firstborn who was able to hold conversations with adults by 2 yrs old.
Every child is different.
My 2nd child now... well, she will talk your ear off; she's 4 yrs old. She does have problems with certain sounds, but, that's alleviating itself as well. I have just been helping her say words correctly.
I had talked to someone at my oldest's school and she said to just wait until my daughter was 4 and see the difference before bringing her to a speach therapist. She turned 4 in Dec. and there has been a pretty big difference already.
I think what my 2nd child was doing was just observing that whole no-talking phase; because the things she comes out with now, its pretty funny... she uses words like 'situated' correctly.
Concerning fluid in the ears... I don't know if a 2 yr. old would allow this... but, ear candles help remove not only wax build-up but also fluid. I've witnessed this myself.
Best wishes!