Further to agreeing with what others have said... If the continual stress mounts to unbearable levels for her, check out the show surrounds in advance, so you know you can take her away to an environment that she can relax and chill at, before returning. Stress builds up when chronic(long term, never ending), until even mild stresses can cause a horse to get to 'the final straw'. But if you can give her even short stress free breaks in between, you can 'reset' her stress levels & then she will handle some more. If you can't do it in a manner that you can do this, then I'd quit doing more than single day shows for some time, until she can become very comfortable with the single days, including being stalled for short spells, and until she's comfortable being stalled overnight at more 'comfortable' places. And taking a *settled* mate with her should help her feel less anxious about it all.