The Maya Medicine Museum (Av. Salomón González Blanco 10, Col. Morelos, tel. 967/678-5438, 10 a.m.–6 p.m. Mon.–Fri., 10 a.m.–4 p.m. Sat.–Sun., US$2) has exhibits on ancient and contemporary Maya medical practices, including sections on childbirth and the five different types of healers: pulse reader, mountaintop prayer healer, bone healer, herbalist, and midwife.
Written guides are available in several languages, and there’s a small pharmacy that sells products derived from the on-site medicinal plant garden. And if you have an ailment, you can request a limpieza (cleansing, 9 a.m.–2 p.m. Mon.–Fri., US$5).
The museum is a project of OMIECH, an association of indigenous doctors in Chiapas [1], and can also provide information on local organizations working in indigenous communities. A cab to the museum costs US$2, or walk north on Avenida General Utrilla, over the hill and past the market (about 30 minutes). Consider combining this with a visit to Moxviquil Reserve [2], which is a short distance further, along the periférico.
Links:
[1] http://www.moon.com/destinations/chiapas
[2] http://www.moon.com/destinations/chiapas/san-cristobal-de-las-casas/sights/natural-attractions/reserva-moxviquil