3year old started stuttering out of nowhere

3year old started stuttering out of nowhere My daughter is shy of 3 1/2 years old. About a month ago she started with a typical C-C-C-Cat like stutter. Now she has prolongation stuttering and has such a hard time just getting what she wants to say out. She repeats the first syllable 10-15x. I believe she’s aware of her stutter now since she puts her hands to her mouth when she knows she’s going to stutter. I recently had her evaluated, but they aren’t telling me much, they keep telling me only time will tell if its developmental. Has anyone experienced this where the stuttering is really bad and then eventually goes away?