This question would be very difficult to answer. However, I do see some parallels in the euphoria of which you mention to some similar experiences I’ve had.
Our brain is complex. There is various chemicals and transmitters that, when damaged can result in mental illnesses. Even the most undamaged brain can have its quirks, even result in some odd behaviours that are not classified as anything resembling mental illness.
The movie “Rainman” is an example of the opposite. His character had autism, a major mental illness yet he like many with autism had a mind with incredible memory and mathematical genius.
Some people with MI have artistic qualities etc. I prefer to label these oddities as “quirks”. They are harmless and unique.
In your case it is similar to a natural “high”. You experience laughter and confidence and all I’m saying is it might well be a quirk of your mind causing it. This high has happened to me- friends thought I was drunk, I hadn’t touched any drink,
Whatever causes it I wouldn’t have much concern about it. If it continues to worry you in a few years then by all means pursue it through a doctor when you are more independent. Otherwise it is a harmless quirk and unique to your personality.
I call my inner quirk- my inner clown. I wrote a poem about him once-
MY OWN CLOWN
I have a clown I hold in my hand
people would laugh, they wouldn’t understand
And sometimes I see him through a blur
I was crying, of course we both were
one day he said I was a clown
”I laugh when you’re up, and cry when you’re down”
I looked closer to this little man I could barely see
this little clown...was a mirror image of me!!...