Help am i going mad...?

Hey I m 15 years old and I have a therapist because I self mutulate,as I went to therapy but left cuz of good behavior...but ever since a while back I think I'm going mad....I see,feel imagine things that make no sense.For exampl today I closed my eyes and I heard a noise as if someone had open the door so I rushed thinking it was my brother but no was there so Yell out his name and he was standing next me in the room we were in when I closed my eyes...I feel things touching me when no one is around as if I have a insect crawling in my skin...I was hospitalized for carving at my skin they thought I was on drug but no I don't do drugs...uhm....I also see people walk in front of me and a fast glimpse away and their gone...I hear voices talk to me every once in a while...my girlfriend left me because she thought i was insane...ever since I left therapy...I'm paranoid...too a extremely unusual limit...Help am I going madd...Ohh and I remembered my therapist used to tell me about gain back my sanity....wat does that mean...plz help I'm on a verge is all of this linked to my self injury should I seek more medical help I'm too scared