Normally breastfeeding baby should have 6-8 dirty diapers at this age if fed enough. Baby at this age growh every fast and need much more milk that before. Probably your baby didn't get enough food. try to eat better and have a lot of milk and soup yourself, and let the baby empty your breast each time. rub the little tummy a bit to help digest.
Do not give a 2-month-old other food or medicine or fluid, unless ordered by doctor. It'll hurt his/her tiny kidney and liver.