My sister has an exam she’s a medical student and everytime she has an exam she gets really bad anxiety and stress.. once even we thought she was having a stroke. 
Note that she does take a medicine but it makes her sleepy so she cant take it now also it is addictive so she only takes it when it’s necessary. 
I’m younger than her but whenever she has an exam i stay up with her all night to make sure that she’s alright and i can never sleep till i see her ok. I’ve always tried to calm her down and help her but my methods are no longer working i never leave her alone when she has anxiety she doesnt want me to leave her alone.
She has been vomiting none stop since yesterday and both of us still have 0 hours of sleep,she’s currently getting ready to go do her exam. Please anyone who’s been through such a thing can you tell me any tips i can do to help her? What worked best for you? I too have been through such situations but my methods are not working and when i have a panic attack or an anxiety attack i like to be left alone so i no longer know what to do . This is not the first time this happens but usually i calm her down a bit

Please also note that therapy is out of question for her my parents can’t afford it currently. I have been saving up so that the both of us can go but she first since hers is more severe and i also want something immediate for now something that will help her before her exam.

Highly appreciate it!