8 year old on antibiotics for tonsillitis (48 hrs) having severe snoring, frog like voice, should i take her t the er? what can they do for her?

Depends: If she is unable to keep up with her fluid needs to the point she doesn't pee at least every 12 hrs, she should be seen. If she is drinking okay, feeding & interacting okay you can monitor this for a while. Snoring is not unusual but the frog voice suggests more a viral or other irritation of the vocal cords. On the other hand, you know her & if she spooks you go in.