Sperical lumps in milk
I would suspect that these lumps are milk protein coagulating, sometimes these little lumps are unavoidable. I also suspect that this means your milk was 'on the verge or going,' and I would suggest that you either use a pure silver pitcher to keep your milk from growing bacteria or you can drop a pure silver item into your milk. Silver will prevent bacteria from multiplying(silver works especially well if you are going to leave your milk at room temperature for any period of time.) Good Luck