I'm going back to work after Thanksgiving after 6 weeks with my son. I've been adding in some pumping and supplementing with formula. So he's gotten bottles of both breast milk and formula sometimes. Now my son is having trouble breastfeeding the past few days. He'll do 10-15 minutes on one side and then start fussing. I've tried calming him and going back to it or switching breasts, but it doesn't seem to be working well. He'll only do 2-3 minutes more once he gets upset. Any suggestions?!?