Oh my goodness, poor things.
It sounds like you have a LOT of work to do in managing water conditions.
Also, it's gonna be said, and its gonna be said a lot - you really should be avoiding handling your axolotls at the best of times, photos through water are fine, but dude... Your HANDS! You've clearly been working on cars all day cause your hands are still caked in oil and whatever! I can imagine its a nightmare to ever get clean hands again after working on cars, but you must stop handling your axolotls, full stop.
Their skin is delicate and sensitive. They also absorb chemicals very readily through it. If you are routinely handling them or their tank with post-car-day hands, this could very well be contributing to the problem.
Your axolotls are lovely, you really need to look at getting tank and water conditions under control and start problem solving here!
I hope we can help you get things sorted.
(Lol @ skint btw)