Hello, I am Rafael. Thanks for asking your question - I'm here to support you. (Information posted here is not private or confidential but public).
I am sorry to know about your son and his grandmother accident.
When a person develops nightmares this abruptly and always around tragedies happening to self or loved ones, it may show how traumatic such event -the accident- was for the person, who did not know how to effectively cope with the emotional impact from it, what led his psyche to fuel fear and speculation in conscious ways - through negative ideation, or subconsciously - through nightmares- about the traumatic event.
If a person shows this problem, it could also show how more sensitive - vulnerable the person happens to be around life stressors or issues, Most times people could suffer higher anxiety levels what make them more vulnerable to develop anxiety disorders, including psycho-somatic problems, including insomnia, nightmares and more.
When that's the case, psychological support is necessary for the person to process the traumatic event, and to learn-develop effective coping skills and anxiety management, what would allow sleep regulation and better resilience to handle new similar stressors.
If we add Cannabis (marijuana), to this scenario, things just get much more complicated, since this drug does create anxiety disorders and mood problems, and it would be unrealistic to expect any rehabilitation from the sleep-anxiety problem while using this or other drugs.
Please look for a professional psychological support, for him to be assessed and then start psychotherapy as soon as possible for all the core issues he may present, what would offer the best chances for rehabilitation.
Does it make sense?
yes. You have said the same things we have concluded. He has stopped the dope. We are making an appointment with psychologist this week. We belive there is some other reason he has not felt comfortable talking with his parents about yet. Thanks for confirming what we saw was not something to play with... we don't want him to harm himself or others.
You're very welcome. Then you are already doing the best to support him, now it is all about him working on himself with the right professional support too. Thank you for your trust.