Dolce in trouble

I swear animals are worse than children at getting sick. Dolce's spay went fine, but now I can see a bump on the left side of her chest and it's big. You can see it just by looking at her. I'm going to try and squeeze her in Monday at 12 or 1 pm before I get to work...Ugh I hope it's not a tumor or something...She just got spayed so it may be an infection, but wouldn't that happen near the stitches?