Yep, my own just resolved this issue. When you are breastfeeding, chances are you are providing good bacteria, and between the solids are feeding bad bacteria. You can consult your local N.D. about treatment. What works for us is dusting the breast with probiotic powder (REUT3 from Emerson Ecologics contains the bifida infantis that mimics the first official bacteria)
In the meantime, make sure there is plenty of liquid in every solid. Especially the rice and grain cereals, make them watery soup if you give them.
But do consult with your local doc to make contact.