Your symptoms suggest that you're suffering from post-traumatic or post-traumatic stress disorder, which is a psychological therapy and mental health counseling that helps you deal with trauma and emotions, and you may need to do a clinical screening and mental evaluation to determine the course of treatment that is most appropriate for you.
I'm experiencing nightmares and flashbacks related to a traumatic event that happened a few months ago, and I'm avoiding it because there's always a feeling of anxiety and a certain situation that causes me.