Totally just a bump in the road. Tandem nursing you are getting more stimulation without pumping! A 7 month old is going to let you know if he/she is hungry.
My daughter and I both got the stomach flu when she was somewhere between and 6 and 9 months (it is all a little fuzzy now that she's three). But what is clear is the image of me sitting on the toilet, puking in the bathtub and either nursing or having the baby throw up on my simultaneously. We got through it fine, but there was definitely a dip in my otherwise over-abundant supply.
Keep yourself well-hydrated. Peppermint tea with a little honey is refreshing and soothing to a sensitive tummy. Add some oatmeal to your diet as soon as you feel like you can handle it...it is also known to boost supply. Try to eat some small bites of protein throughout the day.
Good luck and feel better soon.