First of all you need to discuss to the current lawyer regarding all the issues you are having with the current lawyers, you can try to solve those problems with a healthy discussion.
If this trick doesn't work than you can think to hire another lawyer as you will have to expense the money to that lawyer that could be more than current lawyers and there are possibilities that the lawyer may not be trustworthy. It can take long time to create and maintain trustworthy relationship with new lawyer.
As you said that no lawyer is interested to take your medical malpractice case, so it is better to go with the current lawyer as he is having enough knowledge regarding that case, so he can handle the case very well.
If another lawyer is telling you to fire the current lawyer which means he has no trust on you, and there is possibility that he can back off from you, and moreover you will have to pay to both of the lawyers at the same time. This will be the best decision to keep the current lawyer by your side rather than hiring new lawyer.