New mommy cat with swollen belly just on one side

My cat had a kitten 3 weeks ago and suddenly today one side of her belly has a hard 'lump' the whole length of her right nipples, about 2 inches wide with the nipples in the center. the other side of her  belly is normal. the middle nipple on the swollen side is also bruised.

Sounds like a vet errand. I would guess she got some sort of inflammation there. Very possible she got this bruise infected, and the infection did spread.  If so, this is even more serious than "just" an inflammation like mastitis..

So lets not guess, contact a vet asap.

Seems she to be in pains? If you touch it?  Or got irritated on the kitten if it does it...

  Or run a fever?  It will be also the first the vet asks you when you phone.

So, begin at least with phoning your vet.   ASAP.

Be ready to visit the vet with your mommy cat.  As soon as feasible.

Welcome to our Forums!

Good luck!

Only one kitten? She could have over produced milk causing mastitis, as said a vet visit is needed