I'm Scared...

Few days ago while we were watching TV in the living room I noticed a mouse running around the corner. It's my first time that I saw it ever since we moved in. My mother told me that the mouse is alone. I am really scared of it, I bought something for the mice to be out of our sight. Yesterday, I saw the mouse again so I spread the powder so it will be killed. In the evening after spreading that powder the mouse came into my room walking on the ceiling. Oh gosh I am really scared!.. I don't know how he gets in. I can't sleep well during the night because I'm scared. I think the one I bought is not that effective and needs to get another type.