Inducing

Samantha
I'm 36 weeks and 4 days. I had a doctor app yesterday and he said I was dilated at a two when he did the exam. Since then I think I've lost my mucus plug and I've have a lot of pain in my back and my belly as seemingly been tightening when my back hurts the most. This is my 1st pregnancy and I'm not sure if it's contractions or not. How do I know for sure?