Could I be in labor?

I'm 36w2d pregnant. I went to bed and woke up with really bad nausea and diarrhea pains. I went to the toilet for 20 minutes but the pain is still there. My pain is in my upper abdomen and is more constant than I thought contractions would be. I tried eating a snack, drinking water, walking, And going to the bathroom but nothing has helped. Last night I started having bad lower back pain and now this. Could I be in labor or could it just be a stomach bug? Figured I'd ask here before calling the l&d at the hospital sounding ridiculous.