I've had lumpy does plenty of times. If they miss a feeding with their offspring, I pick them up just before they are going to feed, when removing kits, and sometimes just because the litter was small and the milk production hasn't adjusted to only have 2 or 3 live kits. Generally it's gone in 24hrs. Much sooner if they have kits to nurse. I've only had 1 doe end up with mastitis and it happened while she had a full litter on her. Within a couple days it was obvious something was wrong as the swelling began to spread in different directions, it was extremely warm (rabbits have a higher body temp than humans so just feeling a bit warm doesn't mean anything), and with pressure lumpy stuff started coming out. It's quite different from a doe who is just carrying around a little extra milk.