To answer your question the centro por salud is one block soutgh of Intercam Bank. Go to Intercam, turn south between the bank and Oxxo, left on very next street, then up abour 200 meters. There is a pharmacy next door that normally carries the antidote. Be safe, have someone take you, and if they do not have antidote, The Cihuatlan clinic is at the new hospital just after entering the town on the left.