It is not uncommon for breastfeeding mothers to need to take low dose aspirin, sometimes for reasons in pregnancy or after cardiac events. Whilst it isnt recommended regularly as a painkiller at a dose of 600mg four times a day it is compatible with breastfeeding in low dose of 75-150mg daily.

low dose aspirin and breastfeeding

If accidentally taken at an analgesic dose see https://breastfeeding-and-medication.co.uk/fact-sheet/accidentally-taking-one-dose-of-aspirin-when-breastfeeding