Axolotl organs tend to be purple. Sometimes axies do get a little lumpy - redness in the gills tends to be directly related to activity (more activity, more blood flow)
And yes Aura, if i remember correctly that axie did recover - but the stone was extracted.
The fact it isn't a blockage is only good news. Looking at your story, there doesn't seem to be anything serious wrong here. If the behavior is fine and un-changed (minus small changes for stress from being moved around a lot, and the effects of fridging) I really wouldn't worry right now.
She needs a good environment with good husbandry and lots of observation, not to be transported when there's no real reason for it - transportation is a very stressful thing for axolotls. It's possible that there's fluid build up inside her. Your vet doesn't seem very Axolotl savvy (from the still purple thing). You will need an axolotl savvy vet regardless of any problems.
Axolotls often get lumps on their sides - they are not a straight through system, they have digestive systems that are all twisty and silly like ours. I would suspect it's food/poop going through her system or fluid build up.