Pain in testicles after doing uphill walking on a treadmill ive had a scan and been given medication the scan was clear but i have really bad pain?

See a surgeon: You should see a surgeon to get evaluated for a hernia. Those do not always show up on ultrasounds and require a careful physical examination.

Hernia: Pain in groin and testicle area in a young healthy man frequently is a hernia in the region. some hernias like "Sports Hernia" can be very hard to find. Tendon strains or avulsions are on the list of possibilities. Testicular problem unlikely.