Im on day 4 as well, I remember your post saying you were feeling pretty great on your day 3. Like the other post maybe you pushed yourself too hard. Im feeling ok, just woke up at 1pm lol. I slept good, but my sleep schedule is terrible I couldnt fall asleep until 7am. I have an interview tomorrow morning, hopefully get job and start work soon after so its going to be an intense adjustment. I'm prepared to not be able to sleep until 7am, then interview at 9am oh well.
I would say just take it easy today, it's sunday rest day. Do some chill stuff around the house, maybe a walk, cook something, or just order some food and chill. Hang in there. We both on the same day sober, we got this!