You are fire your medical malpractice lawyer at any time and for any reason. No explanation is necessary. All you have to say is "YOU'RE FIRED!"
By signing a retainer agreement, you are not bound to stick with the lawyer for the rest of the case. If you believe your lawyer has been dishonest with you or is not doing what he/she says they'll do, then FIRE HIM! It's that simple, even if your case is just days away from trial you can still fire your lawyer.