This has happen to me too. There are many ways you can get rid of a spirit.
What i did and recommend you doing is:
1st- You need to rule out that it's not a person that's doing that.
2nd- IF you are 100% sure this is a spiritual problem then do as followed:
Step 1: Cleanse yourself, your roommate and your home. You can use sage to do that, you can use chants, whatever is in your power, use it.
Step 2: Cast a protection spell over your home to make sure no bad spirits enter it.
Step 3: If you do not want to cast anything or don't have ingredients whatsoever, put salt on your windows and doors.
If after all this the spirit comes back shortly after ( 1-4 months ) or doesn't get out of your home at all, then maybe you should banish it. You can do the Lesser Banishment Of The Pentagram or even find another spell/ritual.
However, if the situation get's worse ( You feel touches, wake up scratched/bruised etc.. ) You should either:
- Seek help, from a priest at a church nearby. I think he can and would bless your house. That's a good way to get rid of bad spirits.
- If nothing works ( It will be super odd if it doesn't ) then move out of the house. It's the last mesure to take for you to be safe.