18 weeks pregnant and i cant stand for too long

Ridlid87
Hey ladies I am 18 weeks preggo and today i stand almlst for 15 min to put hair dye on my hair then I have started feeling abdominal pressure.. It is not too much but enough for me to worry.. I have to go to take shower in 20 minutes that means more standing. I am worrying.. does it happen to anyone else.