Dizziness when concentrating?

Ok, my head is spinning! I've been getting this on of for the past few months and it's driving me crazy! I can be watching TV, when suddenly everything starts moving/shaking! The only way to stop it (temporarily) is to look around the room (keep moving my eyes), but as soon as i stop and look at one spot again, everything moves! I'm not tired or stressed, I'm hydrated and I haven't had a lot of caffeine etc... I also don't wear glasses or contacts (If that is relivant) I just don't understand why it's happening? I have been having a lot of headaches recently... But it still doesn't explain it... Any ideas?