Anxiety

How do I get rid of it? I feel like someone's watching, like I'm gonna get hurt, my boyfriend might die, and other stuff like that. I have nightmares about all that. I'm also remembering/having flashbacks of bad memories, and dreaming about how I watched my mother die and struggle to breath. I'm scared. It doesn't matter who I'm with, I always feel this way. What exactly is this? Is I PSD? Is it an anxiety disorder? Help, please.