Should i be woried ?

OK I came home from school, and my dog ran off, I was chacing him for about 15 minutes, When I caught him I sat down for about 40. Then I went to get a drink. Well, when I drank it my side began to hurt sharply , and when I got it down, my side...

continued to hurt very painfully, then I went dizzy, and nearly tumbled to the floor..
Now that the dizzy spell is off, my head and side still hurt..
What could this be ? should I go to the hospital?

well you should just call a doctor and ask him or her about it. it doesnt seem like something to go to the hospital about just yet.

Has this happened before?

Even if it hasn't I would go to see a doctor and see what they think, although, I don't really think it is anything serious

this happens to me all the time. I don't know why, but it only lasts for a few minutes for me. maybe half an hour at the most. when I was in florida, I barely drank anything all day, and when I did I felt like I was going to puke because of this huuuge pain in my side, and I just wanted to go to bed because my head hurt so much... but I don't really think you have anything to worry about. just drink more water, especially after you just finished running

 
I don't think that it is anything to worry about. You created a great demand on your body during those 15 minutes of chasing your dog. Your body was probably just getting itself back to its normal state during those 40 minutes you were resting. It's quite likely that your body wasn't quite ready for water when you drank and the wanting to faint was probably caused by your standing up and your blood not getting to your head fast enough.

If the symptoms continue with frequency in the future, then maybe it would be time to consult with your doctor.

 
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It may have been many things. Did you drink it too fast? If you did and you were very thursty it may have reached the valve between the esophagus and the stomach and not been able to pass through there by slightly expanding the esophagus and causing the pain that you felt. More than likely if it's a rare occurence it's no big deal. However, if you find that it's happens often or becomes more frequent then please talk to you doctor.