Thrush while Tandem Nursing

I breastfeed my toddler (2) before nap time and before bed. And I exclusively breastfeed/pump my 3month old. The baby has gotten trush was seems like every other week for the last month or so and I have treated me and baby twice now I sterilized all binkeys,bottles and pump parts and can't figure out why we can't seem to shake this. The only thing I can think of is that my toddler is the missing pieces that hasn't been treated and keeps passing it back to me and baby? Is this a possibility? Has anyone else had the same trouble?