If you have been vomiting or have diarrhea due to the flu, you should not dry fast. You could do a “dirty” water fast to help your stomach feel better. But you need to ensure you’re getting in electrolytes if you’ve been sick. Seriously, you can end up in the hospital with severe dehydration otherwise.
If this is your first time fasting, I think 3 days is amazing and there is no shame if you stop.
In fact the recommendation with dry fasting (also water but to a lesser degree) is that you slowly build up to longer fasts, but don’t try to do too much too soon.
At lot of people are careful with their diet leading up to a fast, if you’re on keto or carnivore, you can be in ketosis and you will have overcome the keto flu stage. Also being in ketosis may mean you experience less hunger (doesn’t always work for me though).
Another thing to consider, when I did my first dry fast, instead of going straight back to eating, I went into a water fast, if you do this you can take electrolytes and this may stave off your keto flu (assuming that is what it is).
Anyway, again congratulations! You have done very well, enjoy your refeeding (slowly does it).