Some questions---Is this a new machine? Has the machine been sewing properly? Have you rethreaded the upper and bobbin threads? Is this a material you don't normally sew on? Is this a new thread type you are trying?
Now...info I have gleaned after a number of years of sewing. Looped stitches on the bottom typically mean that the upper tension is bad. Have you checked to see that your thread is going through the upper tension properly? There are other reasons for the problem. One that I had experience with was a tiny bit of thread somewhere in the thread path. Another way I caused that problem with an older machine I had, was by not lowering the presser foot. Luckily, my newer machines won't sew if the presser foot is up.