Trazodone caused worse nightmares for me--I had to stop taking it.

What's helped for me with the nightmares is a medication called prazosin. Its on-label use is for high blood pressure, but some VA doctors figured out accidentally that it helps with nightmares, particularly those related to PTSD.

I also really recommend having a sleep study done if you haven't. I had sleep problems for most of my life, and I went through all the usual sleep meds with unsatisfactory results. When I finally had a sleep study done, they found out that because of the particular sleep disorders I had, I wouldn't respond to typical sleep meds, but the doctor was able to get me on some meds that did actually help.