Regarding CHS, it's currently perceived as a subgroup of cyclic vomiting syndrome (CVS). Multiple hypotheses have been put forward, with one suggesting an allergy to neem, given that no organism will consume neem trees. Another theory proposes that pesticides and fungicides might interact or transform during combustion, leading to this condition.
Your mould hypothesis is also plausible. There's a research related to allergies indicating that even after sterilization to exterminate the mould, its toxins could still trigger a reaction.
Another possibility could be an overload of the endocannabinoid system, which could instigate CVS. This could be likened to an animal's response to consuming an excess of cannabis, which often results in vomiting.
On the subject of quitting cannabis, studies based on anonymous online surveys are largely unreliable. Moreover, it's uncommon for individuals to seek addiction treatment for cannabis unless mandated by a judicial authority or parents. The numerous benefits of cannabis, such as pain relief, anxiety and stress reduction, generally overshadow its drawbacks. The debate on the challenges of quitting cannabis is largely driven by those profiting from the treatment of "cannabis addiction".
The difficulty in understanding something is often influenced when one's income is dependent on them not understanding it.