Have you seen your primary care doctor? If not, you need to. The ER isn't going to be able to look for everything or do follow-ups.
This could be muscular. You may have held and moved your body differently to compensate for the pain that started in your lower back. This could have caused your other back muscles to tighten. In that case, you probably need muscle relaxers and physical therapy to get things moving again.
Back pan can also indicate another condition, such as gallbladder, kidney, or lung issues. Sometimes, pain from one area can radiate or refer to other areas. For example, people with gallbladder problems can get pain in their back and shoulder. In that case, a chiropractor would not help.
Regardless, you need to see your primary care doctor for a full evaluation. Write down all your symptoms and when each of them started, along with anything you were doing differently at the time that could have caused it (lifting boxes, working on a project, sitting for long periods of time, etc). Good luck. I hope you find relief soon.