Working pregnant moms

Lisa • Mother of three. Had first child when 19. She had a heart defect and other birth defects but is doing great now. Then had cayden two and half years later and finally my baby boy Skylar 2 years later.
This is my fourth pregnancy first time working since 1st 8 years ago ....I'm 15 weeks along and lately at work I been getting so light headed and start cramping really bad. I'm a janitor so I mop vacuum dust tables chairs stairs bathrooms lots of bending and sometimes lifting...is this normal to get like this or should I bring it.up to my doctor