Something is wrong with Chloe

She is not herself. The last 2-3 days she's been depressed (for lack of better term). She eats and drinks, but hardly plays, always asleep and isn't greeting me as usual when I come home (usually she jumps up and down for a few minutes then follows me around the apartment, now she is just wagging and goes back to bed, not even following me). I feared leaving her this morning, after forcing her on a walk (she just won't budge) she drank a little and didn't touch her food. She might have eaten after I left, but I don't know.
She pooped last night (11 ish) and peed this morning. Her gums are fine, no ticks, nothing hurts as far as I can tell.

I bought a thermometer to take her temp. when I get home. If she is still like this I'll take her to the vet. Any idea?