As the consumer, you have the right to work with whomever you want. Particularly if you have a crisis of confidence in your current agent.
If you've signed an exclusive buyer's agreement with the first agent, however, you might find yourself owing that current realtor a commission, whether you use her or not.
If you haven't signed an agreement with her, she still might be entitled to a portion of the commission (this time payable from the listing agency) as procuring cause. (there's more to procuring cause, than her just being the first one to show it to you).
Make contact with a new agent, and explain the situation. They should be able to fill in the blanks for you.