So I'm enjoying my newly created game and am walking through whiterun and time to level up. My archery was 25 before this point but when I looked at my skill it is now saying 15 and its red?! I checked my magic active effects and I have no disease so its a glitch. Also, if I look at the next available perk where it tells you the required skill level it does say 25.

From googling somewhere its a known glitch which seems to resolve itself at some point but what I would like to know is whether my damage with the bow will be affected now and if anyone has any more experience with this issue?

It's a disease...

Drink a Cure Disease potion or go to a priest.

Open your magic menu, and check your Active Effects. There will probably be something there in red. A Cure Disease potion should get rid of whatever it is.

It's not a disease. I did say in my post that there are no active effects and I also used the shrine in whiterun to be sure.

some piece of equiped armour is giving you a bonus to x skill and a negative to archery as a balance ?
there were some item encants from oblv i think that would boost 1h skill but lower other skills to balance it out?

Disease, piece of armor that gave you stat, also if you use /showracemenu and change your race your skills will get mixed, ;P

Were you wearing an item that gave you +10 to archery then took it off for something better?

I've had this myself. It's a glitch, it should go back to normal when you get an extra point in archery.