1. since you are suffering from the symptoms since the age of 6, any history of injury
to muscles, bones,joints,tendons,soft tissues?
2. any wear and tear,overuse, spine problem, poor circulation, varicose veins
3. since its quite a long time, hopefully deep vein thrombosis
or any clot is ruled out.
4. were investigations like doppler study carried out to rule out DVT? or RA factor,ASO titre were done to exclude Rheumatoid arthritis
5. check your potassium and calcium level, as low concentration (deficiency) result in nerve dysfunction and leg pain.
6. regarding painful vein: have you noticed any symptom like swelling, ulcer,skin change,around the leg?
7. was orthopedic doctor consulted for any compartment syndrome?
8. your health care provider can guide you with further evaluation and treatment aspect, so make an appointment with him for further necessary management.