i might have manifested depression for myself

i 18f, was in a talking stage with a guy who was severely sad all the time and i used to be a pretty happy go lucky person. i also was sort of melancholic and everything but i was not depressed, for sure. this guy was severely involved in his thoughts and like he was upset all the time and used to say that he might not even survive till 21. during the time i was talking to him, i was pretty fine but i did see a shift in my energies, a very minor one. later, after we ended things, i feel that im severly sad all the time and i find myself stuck in the though loops just like him and have started to question my life exactly like him. this is very strange to me because i have NEVER been this person. is this a transfer of energies or have i manifested such energy unknowingly?