Many people who have herniated discs have no symptoms and there are not even aware of the problem. When they do feel pain, it's because the ruptured disc is pressing on the neighboring nerves or the spinal cord. Where the pain is felt in the body depends on which nerve the disc may be pressing on. For example, many people with herniated discs feel no pain at all in their back, and yet they have excruciating pain shooting down their leg. In this case, the bulging or herniated disc is pressing on the sciatic nerve. The sciatic nerve is one of the largest nostrils in the body and runs down the leg, and this is where the pain will manifest. The point however is that just because you might not feel pain in your back, it does not mean you do not have a bulging disc.
If it's presumed you have a back injury, MRIs (magnetic resonance imaging) and CT scans (Computed Tomography) are the best ways to get a proper diagnosis. X-rays do not usually help determine if a disc is herniated or not. Generally speaking, if you have no or little pain and yet you've been diagnosed with a herniated disc, chances are the disc is not pressing on any nerves.
This should not be a signal to not take action however. Even if no pain is present, it is advised that you consult with your doctor or physiotherapist and start core function and postural alignment treatments immediately to avoid your disc bulging any further.