How to tell

How can you tell if you have a kidney infection or just really bad back ache? Im 18 weeks pregnant and I am on day two of this back ache and it’s killing me. I can’t really move without being in pain, when I turn in my sleep the pain wakes me up, I can’t lift my kid with out almost dropping him from the pain. It’s killing me! I can’t take it anymore! I have tried Tylenol, a heating pad, and a warm bath. What else can I do!