And you don't even necessarily need a psychologist/psychiatrist diagnosis to be medicated for mental/neurological conditions.
When I went to my GP after I realized I fit the symptoms of ADHD, she referred me to a neuropsychologist for testing/diagnosis, and then began medication treatment for me after she received the report.
Then, when I went to my current doctor about how I have extremely mild social/situational anxiety that manifests itself purely physiologically, he had no problem giving me a prescription. I explained that I lose my appetite and become slightly nauseous in unfamiliar situations, but my ADHD meds make me extremely nauseous if taken on an empty stomach, so traveling to conferences for work either means I feel sick the whole time or I can't concentrate at all. I literally just asked for a low dose of an anxiety medication, and he had no problem giving me a 30 day prescription of 0.5mg of lorazepam 1-2 times a day only when needed. I described clear symptoms that would be alleviated by that drug so he had no problem prescribing it (especially since it's an insanely low dose and I only take it for a few days at a time with long periods in between).