Hello,
Tubal ligation and tubal implants are not 100% effective in preventing pregnancy. The failure rate depends on method used and several other factors. Breast discharge can be caused by many causes. Pregnancy is one of them. Other causes are use of pills, fluctuating hormones, stimulation of the nipples through sex, underactive thyroid, raised prolactin levels due to prolactinoma, galactocele and early form of breast cancer called carcinoma in situ.It is suggested to consult a gynecologist and get evaluated. You may need a clinical examination and work up depending on the clinical examination results. Do write to me again. I sincerely hope it helps.
Best luck and regards!