Ok... I believe that blocked ducts are far more common than mastitis (which is the full shakes, fever, weakness, etc) and most blocked ducts do resolve themselves. Is it always the same spot you've had the issue in? If so I suspect that mixing up your feeding position might help, it sounds like it's maybe not draining completely (maybe due to a little distortion of the duct from the first mastitis) so a change in position might help the tissue to open up and allow the milk to flow... i think it's worth a try?