I'm facing five drug charges for drugs I've never seen or touched. Is that possible?

My moms house was raided, We had someone staying here that was paying room and bored. They had crack cocaine and harion in their room. In my room they found a small blunt of weed. They are now trying to charge me and my sister with the drug charges because they haven't caught him and they are saying with our rooms being upstairs along with his we are being charged. I don't understand how I can be facing prison time for something I've never seen or touched before. Please help I feel like my world is coming to a end with this situation alone.