negative ip?

I just bought Swain which is 4,800 ip. I had 58 ip left and then i log of to go to bed. The next morning i get log on and i have -4,856 ip. I thought it would go away after a game but so i played a game and then it went to -4,632 ip. Now its been 5 days and i cant buy any rune or champs. Any help on how to fix this?