Need advice

I'm 13 weeks and 3 days pregnant. And I'm feeling drained. I work at Walmart and its close to inventory day and we been working crazy hours yesterday pulled a 12 hour shift and I feel drained and u feel like I can nearly move im worried for my baby today I woke up with cramps and back pain and feel really light headed. Today I'm working a 10 our shift. And I'm honestly scared that I'm pushing it to far. Should I be concern? Should I go to the emergency room ? Can someone pls help me with advice?