See a psychiatrist or therapist. HN is the wrong place for this kind of question. Your kid is 3mo old which most people would consider a good time to take some parental leave if they can afford it, which you can (that would ease the overload of juggling the kid with a job). I'm sure you have figured out stuff like that already: your immediate situation is just fine. So you are experiencing a psychological disturbance that needs a level of help by qualified practitioners who can discuss things with you in detail, potentially prescribe meds, and all that sort of thing. A computer nerd forum like HN can't possibly do that.

That all said, it's completely normal to stress out during life changes. So if this was triggered by becoming a parent, the upset should be a temporary situation that will pass, as long as you get through it in one piece.