N.M.
My daughter and I both have issues with dairy and I can tell you 2 weeks is the very minimum it takes to get out of your system. Give it at least 4 weeks. If you are breastfeeding that means that you must remove all dairy from your diet. Diary is hidden in most prepackaged foods and goes under many names. Here's a list - http://www.godairyfree.org/Food-to-Eat/Food-Label-Info/Da...
When my daughter was a few months old if I eat ANY dairy at all she would be miserable for days.
If your child is sensitive to foods breastfeeding is best especially for the long term. Formula isn't going to give your baby the antibodies and other good things to heal and develop a stronger digestive system.
Good luck!