It's ok Mommy. I am an OB and a breastfeeding Mom as well. Wala namang effect sa baby yon. Pero kung malakas ang amoy nung chemical na ginamit, better use a shower cap everytime na nagbrebreastfeed ka.
In general, pregnant moms are not allowed to dye their hair because of the chemicals and the amonia content. I don't know for other hair treatments though. Best to ask your OB.
Katzumi Hana