Could be a seroquel hangover. That usually happens on lower doses though. Seroquel is a strong med, especially at that mg you're taking.

Have you had your lithium levels checked lately? Drinking enough water with it?

I'm trying to remember what else could happen on those meds but it's been so long since I took them.

Also have you had your thyroid levels checked? Lithium can ruin them. That's what happened to me.