she will be starting pre-k this fall -- your words
Could this be the problem? Often children who are beginning a new school situation have difficulty (and are scared) with this unknown situation. Often, they display this fear and frustration by "acting out". It might be wise to wait and see how the first couple of months go at school. Of course, if you think there might be a physical problem (or you would like "peace of mind"), then by all means, contact your family doctor. I wish you the best ...
Do you know why she is acting out , has anything new happened in her life , new Baby, move of house, family problem, sometimes outside factors affect the behavior, have you asked her if she is feeling okay and why she is upset. It is always good to get her checked out with the Doctor, make sure nothing else is going on , Good Luck