Teenage son diagnosed with JME, now having back pain

My 16-year old son was recently diagnosed with JME. He started on Depakote and other than initial drowsiness and difficulty concentrating, he appears to be tolerating the medication pretty well. Starting on the day he had his first (and so far, only) tonic-clonic seizure in mid-November, he was been complaining of hip pain. It appears to be getting worse and now also has lower back pain, radiating down his leg. It's now impacting his ability to do any physical activity and is in pain when he walks. He's seen a chiropractor for 3 weeks, who recommended lower back x-rays and physical therapy as the relief he was providing was proving temporary. Nothing on the x-rays. Starting physical therapy this week. Was wondering if anyone else has had any experience like this as my assumption is that it is related to the initial seizure. He's dealt pretty well with the impact of the JME, but this potentially impacts his ability to be active at even a minimal level. All the best