I'm actually in online school at the moment and I've also been behind quite a bit, my best advice is try to get in contact with the teachers, I don't know if your online school has a center where you can go in and get help but mine does and if you just tell them what you are going through I'm sure that they can help. Worse case scenario you wanted to take a few days off from school and you'll have to lie about being sick or something and they will understand. I hope I helped.