Aslaam O Allaikum! Dear Doctor My 36 Years Old Sister

Aslaam o allaikum! Dear doctor my 36 years old sister is suffering from loose motion for more than 6 months she has gone to different doctors but she is not getting better doctors are saying its because of sensitive nervous system and it happens when she hears any type of shocking news good or bad! And they are also saying this disease can not be cured! Could you please prescribe something I will be thankful to you...