For example SH will disapprove if you reveal the tadpole to Auntie Ethel but later on she suggests visiting Auntie Ethel to get rid of the tadpole when you ask her about what to do next.
Typical woman, totally immersive!
Joke aside, I think her reaction on that is logical. Telling the tadpole issue with the healer of a druid circle is one thing, who probably can offer a cure, but telling it to a loud prying herbalist in a rather crowded market area is another, who might have yell out and run away or telling it to others, and in that case the folks wouldn't treat you as normal person any more. In fact, I think every companion except Lae'zel and Astarion should feel uncomfortable as well.
So it's not about she don't trust Auntie Ethel in particular, but rather more about the player character been reckless on this matter.
And then, since Auntie Ethel already know the problem, seems to know well about tadpole and mind flayer, and offered a solution, it wouldn't hurt to pay her a visit.
Though there is still an inconsistency in this chain of plots. After knowing what Auntie Ethel's potion did to that tiefling's legs, the companions indeed should be more cautious about this old herbalist and what she claimed.