Baby suddenly fussy?

xoxo

My almost 3 month old is suddenly irritable. She gets super fussy during her feedings and is eating less. She has been chewing on her hands a lot as well & waking up more during the night. Is it possible she's teething or is it something else? I feel bad because she'll start crying during her feedings and refuses the nipple but I know shes hungry because she's not finishing her bottles like usual.