How purple do you mean? There is a condition (harmless) where brightly colored liquid comes out of sweat glands, can't remember the name of it but the colors apparently are vivid. Look up "colored sweat" online and see if you can find it.
Hm - I'm not sure! I'm wondering if it might look purple because there's some old blood that's darker? Are you breastfeeding? If not, I would definitely want to talk to my doctor about any breast discharge.