False Memories

I have been experiencing memories which I can't tell are real or dreams. Stuff like conversations and people's faces I will remember in my mind but I don't know if it really happened or not. Even things like remembering that I went to the shops and bought ham for example but then I look in the fridge and there's no ham, it never happened. And remembering about eating something but then I went to the cupboard and it's still sealed and hasn't even been opened. I'm scared and angry. Am I dreaming these things and they seem real? Why can't I tell what's reality and what isn't? I feel like these memories are being planted in my head somehow but why? They aren't even important things but it's worrying me. I don't want to go to sleep and dream. Is there a way to make sure you don't dream? It's really affecting me. Any ideas or help would be much appreciated