M.B.
You may well have two things occuring at once that are making her need to nurse so frequently. As others mentioned, she may well still be recovering from the bug herself, particularly since it sounds like it was a pretty intense one, so she's needing extra nutrition and extra comfort since she's likely not feeling 100% yet. This may also be coinciding with a growth spurt. I second the suggestion of co-sleeping while you work through this issue. I know it's difficult and is impacting your own sleep, but this will pass and it really is important for rebuilding and increasing your milk supply to be able to continue to meet all her nutritional demands, as well as giving her immune system the boost she needs to get through the rest of the winter flu season. It may also be that you need to increase daytime nursing to reduce her need to nurse at nite. With two other children, you're likely very busy during the day and perhaps making the time to nurse extra during the day will help. And, yes, I know that's tough too with two other kids as I only had to do it with one other kid and I know the guilt when you have to care for the baby and have to use a video as a babysitter, but again, this is for a very short period of time.