17yo son with daily aggressive panic attacks

I've just found this forum and hope to get insight on ways to move forward in my situation as single mum to a very troubled teen in a crisis situation. The panic attacks started about 3 - 4 months ago and frequency and intensity has increased. They are now daily, they are sudden and explosive involving punching walls, throwing furniture screaming and crying he has nothing to live for and wants to die all the time. Each time I am seconds from calling 000 and then they pass. He is nearly 18 and will smoke weed to self medicate. I don't approve but know his attacks will be even worse without it until I get get him real help. The system has not been able to help us so far. Dr won't prescribe medication without trying psychology but we've waited months for an appointment and then my son refused to go. The thought triggered another outburst. I sit here terrified knowing the next outburst could be any moment & most likely before the weekend is over. As I see it I have 2 options. During an episode I call 000. My fear here is that this WILL push his fear and panic even further if that's possible. Instead of threatening self harm, he may act on it. He will be aggressive and I expect police would be called. It would be a risk and cause irreparable emotional scars to be sedated, forcably restrained and potentially taken to a psych ward and he would see me as a mother who betrayed his trust... But he would be forced to get help, hopefully diagnosed and given meds. Between attacks he is friendly, catching up with friends and trying to make plans. This gives me hope. He says the person having the attack feels like a different person he has no control over. He is sad and embarrassed by the damage. I feel he is very very close to finally agreeing to voluntarily getting help. (as opposed to being forced) I called the Mental health triage but he refused to see them so they cannot help me or open a case. If he agrees to get help, with the frequency and severity of his attacks, where do I go for help?? Is there an emergency psychiatrist? Are there any over the counter medications that might help? How can I calm someone in the midst of an attack. I seem to be a trigger and just looking at him makes him more violent. Its only a matter of time before he smashes windows or runs out onto the road. I'm scared, alone and exhausted. Any suggestions please 😥