i agree with Olivia- Morphing is a Very Difficult process for an axie to go through, and something that only juvies have good outcomes from going through(and then only when done under experienced supervision).
Another thing to check out is the current in your tank- if it's too high, the gills can go very quickly.
As to food, maybe try some different foods- earthworms first (may need to try some different types), then move to bloodworms, blackworms (which can be expensive, but if you've got an axie who isn't eating they can be a godsend), pellets, and as a last resort beef or kangaroo heart (very high in fat so not really a good dietary staple).
Heads up, you've done the right thing so far!