I Think My Nieces Roommate Is Drugging Her And The

I think my nieces roommate is drugging her and the other roommates the symptoms are drowsiness, nausea and vomiting. She has been them a capsule everyday and it is yellow and white and they are always dented and look like they were messed with. Shannon wont let anyone cook any meals other than her and my niece can't get out of bed. So I asked the other roommates if she gave them any type of medication or if they noticed the food tasting off. All of them said yes and I want to know what I should be looking for if they ingest any type of toxin? For a few days now my niece has only eatin what I send home and she wont take the pills and is doing a little better do you have any ideas of what could be put in those or capsules or food without their knowledge? please give any medications or toxins that I should I look for around the house. I am very scared for my niece. I really need advise and look forward to hearing back from someone. Thank you in advance.