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.
Its called 15 years of nerdfighteria so you burn out those brain nodes