L.H.
Dear K.,
Friendly disclaimer: I am currently a graduate student for speech-language pathology at CSUN, so I am not an SLP yet. This means that my advise is not professional but I would like to help you feel a little better and also give you a referral.
The courses I have taken on fluency (stuttering) have touched on the symptoms you have mentioned. Normal dysfluency is about 10% of the time for people. (We all get stuck sometimes, start to say a wrong word, or us fillers like um.) If however, the dysfluency is more frequent, and/or and this is important, it starts to bother the child, you need to take steps to help the issue.
CSUN has a speech, language and hearing clinic where you could take her for an evaluation. The clinic is excellent and will provide you with an assessment that you can use to get services for her, or you can bring her for therapy at CSUN. Their number is ###-###-####. The clinicians can also show you techniques to help your daughter with her speech.
In the meantime, try not to worry too much. Your display of tension or apprehension can affect the extent of her stuttering. Praise her whenever she has fluent speech. When she gets frustrated get down to her eye level and let her know that its okay because you love her a whole bunch. Also, if you ever get stuck on a word, or change your mind mid word, etc let her know. For example if you start to talk and say um, um, or cut a word in half to correct "co- I mean cup" immediately point it out to her: "Did you hear that? Mommy got her words mixed up. What I meant to say was cup, not cop." This will let her know that its okay to make mistakes.
On a side note: has there been a stressful situation that you can correlate with the onset of her dysfluency? We were taught that often times what happens is that there is a predisposition to stuttering which is then set in motion by a stressor like a move, new school, divorce, death or other things perceived as stressful for a child. Try to pay attention to when it happens most often (after a stressful day, doing something she doesn't like, etc.) Does she tense up her jaw, shoulders or other body parts when this is happening? Try to get her relaxed with a big hug, a gentle massage of the jaw "for fun" or other ways that you know she can relax with.
Be observant and reinforce good speaking whenever possible. I don't believe that you are dealing with Autism or ADD, but this is just my layman's hunch, as I am not a diagnostician.
Lots of luck and give us an update!!!!