Well Idk if it's a phobia but

I am a paranoiac person, so when I Iook back and see someone who watches me I immediately scream. I began to have this "fear" the last year, everytime I turned back and see my classmate stared at me (cause they said hi) I couldn't help but jumping and shouting. I even had a nightmare about it, when my dreams begin to reform into something scary I usually open my eyes. But, damn this nightmare seemed like a dream; I was watching a theatre show, with quiproquo etc. The end came, the curtains has fallen. There is applause and the silence, the curtains suddenly open and shows the stage in the darkness. The only spotlight illuminates a man disguise in a demon walking while he is laughing and looks at ME. Since that dream I often check my bedroom before the "bed time" look under the bed, I am straaange. The night after taking a shower or staying late in a room I always wonder "there won't be a person who watches me through the door or the window right?"

Idk how I will react if I'm being stalked, better 4 my heart to not think about it(￣∇￣")
I begin to talk about this "fear" to my mum...