First of all.....{{{ hugs }}} ! Been there, done that, no fun at all!!
It could be so many things, including the old thread, maybe the tension on the bobbin thread isn't right.........
Did any of your kids or grandkids touch your machine? Did you turn it off, count to ten, then start it back up?
Try taking out your bobbin and top thread, put in something newer and grab some scraps and try sewing again.
If all else fails, get a good snack, preferably CHOCOLATE and a cool drink, go to another room, put your feet up, rest ten minutes or so and try it again.