loss of speech

my mom had a cancerous brain tumor on left front side of her brain 10 yrs ago she went through radiation and surgery and it hasnt returned she had grandmal seizures for about 5 yrs after her surgery..she went the past 5 yrs without any seizures and yesterday we had to rush her to the er because she lost the ability to speak and her body would tense up like she was stuck in the same position for about a minute or two but her ability to speak would be gone for three to four minutes she would be aware of whats going on around her but cant respond until it passes the drs cant figure out what it is or whats causing it they have done an mri an ekg and xrays and everything is coming back normal the drs say it could be a mini stroke or seizures they arent sure but yesterday she had about 12 or 13 of them and today she has had 2 any idea what this is or what is causing it