Hi Prixten. I'm really sorry about what it going on with your Axolotl
So, I looked up your previous post and I have SOME suspicions. Let me ask a few questions to try to help you sort things out. With the parameters you listed, are you by chance using the Tetra 6-in-1 water test strips? Some people have good luck with the test strips, but the ones I tried were terrifyingly off, which I only found out after I switched to the API master test kit. We are missing some very valuable information such as ammonia levels, filtration, and temperature. Given that you are feeding blood worms and had other fish in such a small tank, my bet is that the ammonia is VERY high. From the look of your little guy I am also suspicious that he may be morphing.
So here are some facts that lead to my beliefs; ammonia will literally burn the skin, which can cause the sloughing that you described and high ammonia ALSO means less oxygen in the water, so they lose their branchial gills. His head shape also looks VERY atypical for an axolotl, so that with the gill-stumps leads me to believe he is morphing.
Suggestion time! So, I would immediately pull him from the tank. Put him in a container with fresh de-chlorinated water shallow enough to cover his head and back, but put a large rock in it so he can climb out of the water if he so chooses, but he still needs room to move around in the water if not. Given his sloughing, I would fridge him to heal. During this time you will need to do 100% daily water changes. Going forward, I would certainly try to transition him to worms. He will likely spit them out if they arent cut up pretty tiny. He needs to put on weight and the blood worms may not be providing him what he needs quantity wise. While you are doing all this fun, you need to get his tank sorted. At minimum get a ammonia test kit. Let us know how that goes.
*hugs* Good luck with your 'lotl!!