Lil Miss Bipolar

We have a just turned 7 months old Beefmaster that we have had 3 weeks.  Like I said in a previous post, this is our first year showing. I might have moved a little two fast with her because she was doing so great. She was no trouble to break in the beginning she just started leading. We even showed her after having her one week! She went to another show this past weekend and did great in the ring but for some reason just snapped when she came out & tried to bolt and kink & do anything to get away from my daughter. My daughter is 11 and held on but cried after. She is defiantly still hyper aware/skiddish of random things. Like a Walmart bag stuck against the fence, which is understandable. We worked with her all day Sunday and she was a dream then last night we get home from work about 5:30 and I tell the girls to start working their cows. She acted up when my daughter took her out of the pen so I took over and she was acting great for about 30 seconds then snapped. She did everything in her power to get away from me even falling down once then jumping up. I some how managed to hold on in finally got control of her long enough to throw the lead rope over the corral bar to pull her head up. I don't understand why she is staring to have the snap moments then goes back to being ok. This might be normal and I know we have only had her a short time. Our other heifer bonded to us quickly but it seems this one is still not sure about us. She will not come up to me in her little pen but he won't do anything if I walk up to her. She just shys away in the corner. Is there anything I can do to help her get over the snapping episodes?