“Can I go to the ER for back pain?”

Yes, you could go to the ER, but I would not recommend it for what you describe. Unless the pain is excruciating, my first recommendation would be to see an orthopedic surgeon in their office. If your pain were excruciating, I would recommend an orthopedic urgent care center or an urgent care center. While the ER would see you for a little bit of pain, you may end up having to wait quite a while, it is usually more expensive, and they will probably recommend that you follow up with an orthopedic surgeon anyway.