That doesn't sound right at all. I wonder if your grains got encrusted with the milkfat somehow & that disrupted it. Are they yellow?
I've been making mine for a few weeks with the same grains, from raw whole cow milk. I leave mine out at room temperature every time. I put the strained stuff in a jar in the fridge afterward if I don't drink it right away. I keep it going every 1-2 days (however long it takes to finish) like this.