I would say that she may have had mastitis and it is either an abscess or was an abscess and healed over and is now just a scar type bunch of tissue. If that is the case, getting her in the chute and trying to get some milk out of that quarter would be a way to see if that quarter is even producing. If it seems she is producing less milk, then she very well might be... and may not even be making any milk in that quarter....