Lil....gently, I tell you our grown kids cycle and often do better for a while after they do something illegal and get called in on it. Round two. Or three. Or a hundred.
As long as he is smoking spice and doing other drugs possibly, he wont' do better in the long run and the shelters will forbid him from smoking weed or spice while he is there which is why many of our grown kids refuse shelters and would rather live on the streets. They also have rules in shelters that our grown kids need to follow, often including a curfew and a code of behavior. I volunteered at a homeless shelter. The people were treated well and dinner was delicious, cooked by church ladies, but the clients slept on mattresses with blankets. We didn't have beds. Still, if somebody needed to talk, a volunteer was always there to talk. They were not allowed to go out at night and come back in though. You came in and stayed in. We served breakfast and sent them out with bag lunches, but they had to leave at seven. Many went to the library or laundromats...24 hour places in the cold. Many didn't mind the cold and didn't try to get out of it.
The majority were vague about their backgrounds. Most did allude to drug use and being kicked out of relatives and friends homes...this was sort of their last straw. We set up work and therapy appointments for t hem. Social workers would help them get welfare and food stamps and a medical card. The majority never showed up to appointments. But some did. Your son can get better even now, without living at home (sometimes that is a hindrance). Help is in the community, but he has to take advantage of it and one thing he needs to change is the constant drug use. Most jobs do drug test. Spice doesn't show up, but it would affect performance. Pot...well, you know it shows up.
Maybe your son can find out about a rehab. To me, that would be the most significant change your son needs to make in order to function in this world. Some people smoke weed every day and can function. Some alcoholics can function too. Your son is not one of those people. It is impacting the good values he obviously was taught and is seriously imploding his ambition and morality. The drugs are his enemy, but he has to see it.
If it were my kid, I'd be looking for a rehab and give him the address and phone number. I did that for my daughter, but she ended up leaving the state with her brother and quitting on her own. She saw how drugs were affecting her life in a bad way. She didn't want to be that person anymore. Your son can make the same choice she made. He doesn't have to hang onto the idea that chronic pot use and spice are harmless to him. They obviously aren't.
Hugs to both of you and I hope things go well at the counseling session. Of course, this is just my own opinion. Take it for the .02 it is worth. I care about all of you and just want your lives to get better.