Taffy:
The poison ivy rash is caused by a hypersensitivity (allergy) reaction to the
plant that occurs within your own body.  The rash does not secrete toxins, the
only problem would be your pain if the rash spreads to your areola.  Be
cautious using sodium bicarbonate on the breast, the sodium level can cause
dehydration if large amounts are ingested by your little guy.  You might get
some relief by rubbing ice over the rashy area.  This worked well for our
daughter's chicken pox.
Feel better soon!
Catherine Watson Genna, IBCLC