38 weeks, unsure if should be concerned

38 weeks + 4 days pregnant. I work overnights still at a local hospital as a phlebotomist, so I'm on my feet walking most of the night. Last night i started to have BH that made me feel short of breathe. Not painful, just really tight & uncomfortable. Towards the end of the night my lower belly began to ache intermittently, similar to menstraul cramps. The cramping is still coming and going but there's no rhyme or reason to it. It wakes me up then i go back to sleeping. My last appointment I was 80% effaced & 1.5 cm. Idk what to do. If this keeps up, I have to call into work tonight which i don't want to do. Help!