What Causes Sudden Onset Of Memory Loss With History Of TIA?

i am wondering if my 80yr old mother is having TIA s. she had an episode around christmas where she called me on a sunday asking who all the other people were besides mary and joseph in her namger scene and what was she supposed to do with them but she doesn t remember calling me. the next two days she called me inquiring who her grand children were as she was addressing her cards. tuesday she remembered more than monday. she has had 4 of these episodes in the last yr and a half. where the first day is really bad and then each day after gets better until she is almost back to normal.