What Is The Severe Pain In The Groin Of A Child?

My 8 year old son has been having severe pain in his groin area, where leg attaches to hip...he has grown 1 inch in 7 weeks and I am thinking they are growing pains. He is so embarassed but the pain has him bawling in pain and can hardy walk...picking him up hurts because his leg 'hanging' hurts. I have put a heat pack on the area and have tried to massage and stretch his leg...that hurts too.