I've been isolating myself off and on for the last 4 years usually once a year. These isolation periods gradually start after periods of me being pretty/average levels of social. I'll be productive and normal for a couple months, but then i start to 'fade', I'll start having less to say to people and feel awkward after a lot of social interactions. i try to fight these at first and continue hanging out with people even if i feel i have nothing to contribute Conversationally. Eventually i feel so boring and awkward however that i start avoiding people for a while, until i feel recharged again.
Antidepressants and anti psychotics have not helped with these phases unfortunately.