Why would my 14 year old son have brown urine and hurting I his back

Hello Anon

It sounds like your son may have a kidney infection - was he tested for that? This condition occurs when there is a bacterial infection in one or both kidneys. The kidneys remove waste (in the form of urine) from the body. They also balance the water and electrolyte content in the blood by filtering salt and water.

Symptoms include:

Pain in the abdomen, lower back, side, or groin
Frequent urination
Urgent urination that produces only a small amount of urine
Sensation of a full bladder even after urination
Burning pain with urination
Fever and chills
Nausea and vomiting

A kidney infection can be quite serious - please bring him back to the doctor for further evaluation.
Best,
Susan