I suggest you eat normal until you feel better. If you want to fast, ease into it. Try OMAD for a couple weeks. Then try 2 day, 3 day, etc.
I did the above for a month before I did a 120 hour fast.
I feel that OMAD has ruined my thinking process into believing that eating 3 meals a day or even more with snacks is a bad thing. Don’t know if anyone else has that feeling. I’ve been doing it for 2 years now and I will occasionally eat normally every now and then or holidays.
Salt, magnesium and potassium are your friends. Use them liberally while fasting. Also - why would you undo everything you did with fasting with more carbs? That’s not the wisest idea. Break your fast with a good bone broth and salts. Then make sure you eat high quality proteins and fats. Maybe a couple pickles. Go slowly into the fasting world and make your body work for you with applying low carb high fat to your re-feeding time span.