My son has nightmares

My son has been having trouble sleeping though the night.  This mainly started after the beginning of the year.  His dad and I divorce over 1 year ago.  He found out after Christmas that his dad is going to have a baby with his girlfriend.  Since then he has only slept through the night 2 times, otherwise he comes to me and tells me that he has been having bad dreams and often describes portions of them.  Before he found this news out he may have only come to me in the middle of the night once or twice a month.  I am concerned about him and worry that he is not getting the rest that he requires.
I might also add that my son had a tumor removed (partially) from the brain-stem when he was 5.  There is a part of me that worries that there could be some correlation.

[Suri123]

Hi, relax! how old is your son and how is he doing otherwise. He may be recollecting old times and may be he is frightened to sleep alone. It is good to see a neurologist so he can be re-examined for his brain stem surgery also. Keep posting your thoughts and any visits. Take care.

[Suri123]

Hi, hope your son is doing well. Did you take him to your doctor and got sleep study done, can you share your inputs. Please update the section. Take care, bye.