I have extreme pain in my legs that feels like growing pains but i am 20...what is wrong with me?

Impossible to say: First of all, there is no such thing as growing pain. Secondly, it is impossible to even guess based of the little information you provided. Have a doctor evaluate the issue.

See your PCP: It is a very common condition. Legs contain a number of different anatomical structures and tissue types, a wide variety of conditions and injuries can cause leg pain. Proper diagnosis is the key to a successful treatment. See your PCP for evaluation and tests.

Tight calf muscles: This problem can be caused by an imbalance in the feet which is often treated by custom make orthoses or by tight muscles in the legs. Please see your podiatrist and have him check your feet and circulation

Extreme pain in legs: should be evaluated by your doctor or urgent care if it does not resolve with massage or mild OTC pain meds. Dehydration can cause muscle cramps and a change or increase in activity can be associated with shin splints, muscle fatigue or even stress fracture which is all painful. Women on Birth Control are at slight increased risk of blood clots as well which can cause peristent pain.

Leg pain: Your pain may be due to restless legs. A neurologist may be able to help you

Leg Cramps: Hi How long the pain has been going on?? If it is worsening or not improving then you may need blood test to check for electrolytes, thyroid, cbc, ESR etc and imaging studies.