It can be a combination of all of these things. I'd cut out all bubblebath, bath salts, wipes, soaps - you only need water or you can mess up the balance of good flora. Antibiotics will also disturb the balance of good and bad bacteria. Obviously wiping front to back is very important. Thrush/yeast infections love sugar, so cut out that where you can and lots more fruits, veggies, pure juices that you make from home. You can get kids probiotics from health food stores or chemists and also up the garlic. Apple cider vinegar in the bath is definitely a good help. It will take time to build up good bacteria again so it will need a little time.

Sounds like an anti-fungal is needed for relief, but you need to make lifestyle changes to make sure this doesn't happen again as creams are only a bandaid fix.

Check out this article for lots of info. Thrush / Yeast Infections - Take Control of Thrush