Sounds like your baby is on a nursing strike. This is common in babies between three and eight months old. It could happen because of changes in baby's routine (i.e., you going back to work) or due to other factors. Nursing strike usually only last for a few days (but could go up to 10 days). Here’s what you can do. During the strike, you need to focus on
i) expressing your milk: pump according to how often your baby was breastfeeding. This will help ease uncomfortable breast fullness and maintain your supply.
ii) Feed your baby: a cup would be a good choice. If you can, avoid using the bottle. Using a bottle would satisfy a baby’s need to suck and may prolong the strike.
The strike could be brought on by a number of potential causes. You can refer to this list to see if your baby is having any of those mentioned:
http://www.nancymohrbacher.com/articles/2013/1/26/is-your-formerly-nursing-baby-refusing-to-breastfeed.html
This is also another great article highlighting some common causes and what to do during the strike: http://sg.theasianparent.com/when-your-baby-goes-on-milk-strike/
Hui Qun Ng