Can u sue a Nurse Practioner for the wrong Diagonsis?

My mom had me take her to the ER friday night at 5pm due to having numbness in her left arm/hand.She had tingling as well and couldnt hold anything etc.We had a NP who took all her info.med info and did all he stats.The NP did everything in Triage and we Never went to a reg room.He told mom she has Carpal Tunnel gave her a brace.Mom told him she was afraid it was a stroke and he said if it was she would be dead by now.We left the Er the next night moms driving changed where she was all over the road,by the night time she was forgetting to shut the fridge,shutting the tap off etc.Sunday morning we went back to the ER after she called her own Dr and he said to go back.They took her info moved her into a reg room and did a CT.They CT showed a stroke so she was admitted.She talked to a Nurologist and she told mom her stroke happened tuesday so them telling her she had Carpal Tunnel was wrong and they should have done further testing.Can you actually sue the NP cause he didn't do any testing with her claims?? She talked to 1 lawyer and he said No,but this is clearly a case with evidence that it happened prior to her first visit in the ER.