1) Tingling, numbness, pins and needles accompanying leg pain tends to be indicative of nerve involvement. Experiencing the symptoms along with your leg pain makes it more likely to be sciatica.
2) Sciatic nerve pain tends to radiate down the back of the leg or deep within the leg. Pain along the side of the leg, especially if it goes only to the knee, is more apt to be muscle pain. Pain running down the side of the leg is likely to be pain in the iliotibial band-a muscle that runs from the hip to the outer side of the knee.
3) Although this is not an absolute, pain that runs below the knee is much more likely to be sciatic nerve pain than muscular pain. If the pain is going into the foot, sciatica becomes even more likely.
4) If the leg pain worsens with prolonged sitting, that indicates sciatica. The sitting position puts more stress on the sciatic nerve roots as they exit the low back. The longer one sits, the more pressure tends to be put on the sciatic nerve roots.
5) From the seated position, straighten the leg or legs that hurt. If the pain increases, that tends to indicate sciatica. Straightening the leg stretches the sciatic nerve. If there’s irritation of the nerve, it will tend to cause more pain. Note, hamstring pain which is the muscle that goes from the buttocks down the back of the leg to the knee, will also hurt more with this type of stretch.
6) From seated position, tense your stomach muscles and push down into your pelvis (like you’re trying to use the toilet but you are constipated). If this causes more pain down the leg, it indicates sciatica. It also indicates an issue with one or more discs of the low back that could be irritated and pressing on the sciatic nerve roots.