Since the baby is already on formula milk, therefore it will be safer to give her formula milk today to avoid exposure to the extra dose of methadone
that you took today. But please keep a close watch on the baby as she may show signs of methadone withdrawal, as she has been getting methadone daily through the breast milk. Please also try to taper off your methadone dose as soon as possible. Try using over the counter medicines or topically applied analgesic ointments
for back ache. Methadone is not a good option for pain relief because suddenly doubling the dose puts you at risk of death from from respiratory depression
. Please do not do this again.
Hope this helps you. Best wishes.