Thank you for the information,
The pain in the back is often found in young people whose work involves physical effort.
In some cases it can be due to weakness of muscles of the back.
Regular exercise to strengthen the back muscles often help.
In other cases it can be due to slipped disc, osteoporosis, any deformity of spine , infection or growth.
The pain which is going down the leg can be due to pinching of the nerve at the spine.
This can be caused by slipping of disc & pressing on the neve.
An examination by doctor is necessary.
X rays / scan can be needed too.
Till you see doctor try to keep it at rest.
You can apply ice for 10 -15 min wrapped in towel keeping off in between to get the the temperature to normal.
You can also take antiinflammatory analgesics
like motrin or aleve after food to reduce the pain.
I hope this information will help.
Please ask if you need any clarification.