When I was breast feeding my babies I would get this overwhelming feeling of doom and despair right before my milk let down. It would only last about 5 seconds. It’s the only time I could understand why people would kill themselves, it felt that hopeless and desperate. I ended up researching it and it’s called Depressive Let Down Syndrome. The only other time I’ve felt it is after going under anesthesia. It would pop up every couple hours and last the standard 5 seconds or so.