Yes, see your doctor although it's probably not an emergency. Most cases of sciatica (which is caused by a pinched or herniated disk in your lower back) will go away on their own after a few days of rest. (many of us have had it during pregnancy, for example - I know I did.) Use ice packs, not heat, to try to shrink the swelling in the muscles around the disk. Use an anti-inflammatory like ibuprofen. Don't try to push it or do a lot of stretching. Avoid lifting.
My husband (whose family has a history of back problems) ended up having to have back surgery earlier this year for sciatica, which is why I know more than I want to know about it. It's not likely that your injury is as bad as that! If it still is bothering you after a couple of weeks your doctor might send you for an MRI to look at the disk.
Chances are good you'll feel better after a few days of rest. But personally I'd get a medical visit on record just in case you later need to establish that the Gurnee Mills visit was responsible in case you need to bring a lawsuit against the violent shoppers if your injury does end up requiring expensive treatment.