Just went to level up and two-handed (which I use a lot) has dropped to a red 25. I can't choose another perk for it now. The strat guide doesn't even mention this. Any ideas?

Did you go to jail recently? One of my loading tooltips said that skills will atrophy if you get sent to jail for a long period. Could be the reason.

Maybe you're poisoned under the affect of a hostile spell?

maybe its a disease?

No only skill progress goes down like say you are 98% to getting form Two handed up to 34 form 33 well after jail time the progress will go down like say you get imprisoned and now your 64% towards the next skill point.

There's no active effects and I haven't been to jail.

I had this as a result of one hand training, then pick pocketing the money back from the trainer, it eventually went. I'm pretty sure it's a bug to do with using a trainer. Did you use a 2h trainer recently?

this happend to me and my bow, I had it at 40 and it dropped to 20. it mentioned anywhere that something has effected me or had a lasting effect. It stayed with me for a while but went back to normal after sometime. svcked because bow was my main.