Why do I have a massive saliva production thanks?

Excessive Saliva. There are many reasons for excessive saliva, most due to use certain medications, that cause "cholinergic" release, the neural mechanism for excessive saliva. Go see your dentist or an ENT to get an opinion on why.
Could be medication. Saliva overproduction can be due to antipsychotics especially olanzapine. Reflux or gerd, serotonin excess (high doses of medications or multiple meds that increase the concentration of neurotransmitter serotonin), mouth ulcers or infections can also cause sialorrhea. Jaw fracture or dislocation, tonsillitis and certain neurological disorders can prompt it by decreasing the clearance of saliva.