Period Pains for hours ?

How long is it normal to have period like cramps ? I'm asking because since last night I've been having period cramps on and off they are light but noticeable. I've drank a lot of water and rested and it hasent helped. My stomach also hurts I've used the restroom 3 times since last night and my stomach ache seems to makes the cramps worse. I'm 17 weeks pregnant with twins. I called my dr yesterday because it looked like I lost apart of my mucus plug and I was cramping (before I lost some of plug) she said the plug isent a big deal and to relax and drink a lot of water. Idk what to do