Do i have mental problems?

when im alone at night sometimes i get really scared and get cold shivers, i hear things and feel like im not alone, and it always feels like someone is out to get me, or like someone is going to kill me. i am constantly looking around to see if peopel are there, or if i am listening to music i have to take off my headphones, or pause the music to see if i can hear anything, it gets to the point that i cry. i have weird thoughts, and i cant ever explain them to anyone, and when it feels like i can, i cant remember them minutes after. i often have really bad mood swings, one minute im really happy, then the next i am either really angry, or upset. it really scares me, and it scares me even more that i cant talk to anyone about it because i think theyre going to think i am crazy and put me in an insane asylum. sometimes i get really upset about how insane i feel, and ill cry for about ten seconds, and ill be completely fine again. sometimes i think about all of this, then the next second it feels like nothing is wrong, like none of this has ever even happened to me, i question myself when this happens, as if i am someone else, even when i look in the mirror sometimes, it looks like someone else.. what is wrong with me.....? am i just imaganing all of this? or is it all real...?