Hi,
At around 6 months babies go through a growth spurt, they need to feed more often to increase your supply, so that could be it. Also, you mentioned that you were sick and that definitely can affect your supply. You will need to take as much rest as you can, I know how impossible this seems when you have a baby and toddler, but at least drink a lot of water and have a good diet.
Another thing, I remember when my dd was 6 or 7 months old, she was also waking more at night and I nursed her, she had no apetite at all for her morning feed. She could actually go from 4 am feed till noon :shock:. This lasted a week or so, later she went back to her normal feeding pattern.