Waking up with a sore throat or cough can be a sign of gastric reflux, cause youre lying down for a while it might back up there whereas you usually have gravity to hold it back. Especially with constant nausea. Although you said this all is only like a week rather than loooooong. Depending on where you live, might be allergy season too.

TBH, if you got nausea, fatigue, feeling bleh, sore throat (?only in AM) I would sooner guess like the flu or whatever. Just keep track, if its not getting better go see a doctor for proper advice. If its suddenly worse, go to ER. Just keep up healthy habits while youre waiting to see which way it goes.