I am dreaming bad dreams and feeling that something bad will happen knowing that there is no reason to feel like this why & what to do ?

Anticipatory anxiety: It looks like you have "anticipatory anxiety", one of the common type of anxiety disorder, All depends how long is this been going on? If more then 4-5 weeks, more days than not, it may be significant, and should be looked at, nightmares often accompany daytime anxiety. At first try obay sleep hygiene, and stress management, a few psychotherapy sessions might help before any drugs

NIGHTMARES: We all dream every night & don't remember the dreams unless there is a very upsetting reason either because of physical illness or emotional problems. Have a physical exam by a Dr. to know if you have a physical illness. If cleared consult with a Clinical Psychologist with expertise in multiple types of psychotherapy to help you with ZOOM & a Psychiatrist for medication & possible sleep study.