Destruction Not Leveling

[Sines]

So, once I hit dual enchant, I decided it would be fun to add Destruction and Conjuration to my character, with the nice little convienent presence of 0 cost spells. Sure, I'm doing proportionately terrible damage (because nobody is selling things higher than Flame Atronach and Firebolt), but hey, I'll grow into it.

However, I've fought a dragon and 2 mammoths, and there doesn't appear to be any improvement in my skill.

100% mana cost reduction isn't supposed to prevent me from leveling, so that's not it. The only mod I've used in this save, besides Sky UI, is a mod to allow a race change without breaking the game. It's only obvious side effect was giving me a free level (which I console commanded away). I had since gained several levels with my skills increasing as normal. The mod doesn't change your skill levels, and I changed from Redguard to Breton, which (if it did) would have resulted in -5 Destruction. However, an effective loss of skill would likewise have happened in all my Redguard skills which leveled fine.

My Conjuration seems to be leveling just fine, in spite of it's +10 racial change bonus (if it had applied, which it does not). It seems a little slow, but that could just be my imagination.

I'd saved the game, turned off the race change mod (since I didn't need it anymore anyway) and fought another mammoth, with no improvement. There doesn't seem to be anything that would cause this that I can think of. Honestly, some weird quirk left behind by the change race mod is all that I can think of, given that a google search doesn't turn up any results on this.

[Sines]

Okay, I believe I've figured it out. Or at least solved it.

After installing the Unofficial Skyrim Patch and that not working, I did the following.

Using the console command to grant skill experience, granting myself a couple of hundred XP didn't appear to push the bar at all. Just for curiosity, I gave myself 10,000 XP and gained 7 levels. I then reloaded a quicksave, and gave myself XP in 1000 XP chunks, until I leveled up. I was about 30% into the next level when I did that. After this, my XP seemed to increase at what is probably a normal rate.

I think what happened is that the XP required for level up somehow got insane for that level. However, once the level was obtained, it read the XP for next level up as normal.

People not willing (or not able) to use Console Commands could probably solve this in game with a trainer or skillbook.