Thespikes on the top if the aloes lower set of leaves could have punctured the leaf above its flesh and caused it to slowly die, its happened to mine a few times, just remove the dead leave with scissors by cutting at the base of the leaf near the stock, it will be fine. But id suggest sticking a piece of Perlite or a small rock pebble between the bottom and upper leaves spikes so it doesn't happen again.
Also use a pot with drainage holes in a mix of 50:50 cacti and succulent mix and perlite, Sift the heavy material outta the cacti and succulent mix (the sticks and forest material) outta it with a grate or a small plastic pots drainage holes shaking it do it strains the bigger sticks and stuff outta it before adding the perlite. And only water when the soil is dry to the touch.
Aloes have quite large fleshy roots, but don't go mad with the pot size. They are reasonably thirsty in growth (summer for this one?), but still don't like sitting in masses of wet soil for too long. Unless more leaves go quickly then it doesn't look fatal.
Use a pot about a half an inch to and inch bigger then the plant's root ball, clear all the old soil from the roots before repotting with the new soil mix. Goodluck