I've had this happen to me when the thread has somehow come out of the threading "whatever" on my machine. Usually, if I rethread the machine, check the bobbin for any extra lint, and if so clean out the lint on my machine and that generally works well. As much as I hate to say it, it happens to all of us, but you will have to rip the stitches out, as you will not have a seam that will hold up.