What Causes Dizziness And Light Headedness While Running?

Hi I'm a 14 year old girl. I began running for 15 minutes every day for the past 2 weeks and everything was great up until the last time when I was running, I began to get more tired and sweaty than usual. When I finished, I got really dizzy and lightheaded and everything began to turn white. It seemed to go away after drinking some water and resting. I took a break from running for 5 days then today I biked for 30 minutes and when I finished, the same thing happened except this time it didn't go away after drinking water and for about 10 minutes, every time I moved, the same thing would happen again. Now i have a pain in the left side of my head and in my eye. Should i be worried?