Dilation going backwards??

So i was wondering if this is even possible??? Ive been dilated to 1 cm since 33 weeks. Well at my 37 week checkup im 1 cm dilated and 20 percent effaced. My 38 week checkup im 2cm dilated and 20 percent effaced. Last friday i made an er trip for cramping, they told me im 3cm dilated and 40 to 50 percent effaced. Well today i go in and get my routinely cervical check my dr says im 1cm dilated and 30 percent effaced. How in the world did this happen?? I was in total shock. Im so aggravted. This is my 3rd baby. My last two were delivered at 37 weeks and 38 weeks. Please help.