Why does the muscle near my tibia cramp?

I am an 18 year old man and for about two years now, whenever I am asleep at night, I have huge muscle spasms in my lower legs. One second I am asleep, and the next I am clutching my legs and moaning in severe pain. This lasts for a long 30 some seconds then it stops. This has only been happening for the past two years. Why is that and how can I help it?
Answer:
You still could be having growing pains, or your body is lacking in a vitamin. These cramps could also be due to dehydration. Drink more clear fluids and see if this doesn't help. Most people don't know they are dehydrated until it gets too severe. Recommend you see a Doctor for some real professional advise.

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