What should I do? Bad back pain and nausea?

I'm having horrific pain in the lower right part of my back and changing positions and moving around doesn't help at all, and this morning I woke up nauseous. Tried to go to church but had to leave after 20 mins, it was so unbearable. I haven't puked yet but feel like it's coming any minute. I'm 22 weeks pregnant and it doesn't seem like morning sickness (plus it's kinda late for that). I'm scared about listeria and preterm labor and idk if I should go in to the hospital and ask for blood work and a non stress test or if I should wait it out. We've met the deductible on our insurance, so it wouldn't cost anything to go in, but i don't want to go in if this is all normal. It's my first pregnancy tho so I don't know :(. Thoughts, anyone??!