Any place that sells tackle usually also stocks live bait. Bait/tackle shops, some gas stations depending on where you live, and stores like Walmart or farm and fleet supply stores often carry live bait. Some hardware stores too depending on your area.
I'm amazed your buddy is alive in that condition, that's super skinny, like wow, I couldn't believe the age when you said three years. She's so skinny. The goal now would be to get her to eat anything. Frozen bloodworms, small chopped pieces of nightcrawler, brine shrimp are probably far too small for this size so maybe not them.
While feeding is the most important thing, I would also recommend going a bit slow to start so you don't overfeed her. Its easy to shock an animal that is emaciated by giving them too much food. Offer a chopped piece of worm a few times a day to see if she takes, or whatever type of food you want to try to entice her to eat. When she's eating and passing waste successfully you can bump up the amount fed.
I would also do a full water parameters check, ammonia, nitrite all that. Just in case. If she's been in that tank for a while then you've probably cycled it, but perhaps there was a crash and the water is off and that's why she's refusing food.
Axolotls typically lay like over 100 eggs. So unless you have a really large and super aggressive snail, I doubt it ate all the eggs if she did lay. I'm assuming she's laid before with you, is it typical that she would only have a few eggs per clutch? Was there a male in with her before? If I got my life cycle info right she shouldn't have clutched unless she picked up a spermatophore from a male.
Hard water shouldn't be too much of an issue, they prefer harder water as opposed to soft. pH should be around middle 7s. 7.4-7.8 a pH of 8+ is nearing the higher range of where I would be comfortable with. My tanks sit at 7.6. But I'm not sure if a high pH would cause this... I just don't know enough about axolotls.
An adult axolotl can go a week without food without showing adverse signs, so I'm not sure what happened here to make her so emaciated in such a short time. Going off feed for three days shouldn't cause her to become skin and bones.
Perhaps there's someone with more experience that had something similar happen to one of their adults. I hope she pulls through! They can be amazingly resilient. Just try offering small amounts of food to get her to take, and monitor after to make sure she doesn't regurgitate.
