Katie notes:

<<  I too experienced a very brief feeling of
 melancholy when my first breastfed baby would stimulate letdown. I tried
 to describe it to several people and the closest thing I could  compare
 to the feeling is intense homesickness. It was never a real problem for
 me and it faded after a few months. I looked for references to this
 symptom in the medical literature and never found anything.

 Anecdotally, several women I know who experienced severe, clinically
 diagnosed PPD have told me that they felt worse when breastfeeding. >>

I had one mother who told me she felt as though she had fallen into a "black
hole" when she breastfed.  It would last the entire feeding, and then she
would be fine.  She called me at about three months -- i wondered if it wa her
reaction to increased levels of prolactin, and when those leveled off at about
4 months, she would feel better.  And she did.

Jan