always exhausted

I've been eating healthy and trying to exercise but I'm just always so exhausted. I meal prep on Sunday for the whole work week, and I'm trying to stay away from processed foods. my breakfast includes 2 hardboiled eggs, half an avocado, a yogurt, and a coffee. my lunch is normally a protein, starch, and a veggie. and for snacks I have cut fruits or veggie. lately I've been sooo drained, a constant headache and my eyes are super heavy. I don't drink sugary drinks, only water, and I'm trying to be better about drinking more water. I'm 24 years old, but because I like to be in bed by 8, I feel like an old lady. my work day is 730 to about 3 or 4 , and I work with ages 1 to 4, normally keeping one age group for a full day. it's strange because normally I'm never this exhausted. today I'm babysitting and I feel so bad for the child because I'm not ass hyper as I normally am. I had a coffee, but that didn't help. my eyes are soo heavy and I wanna sleep all day. i don't think it's my period because I've been like this for a few weeks now. am I maybe just overtired? Im not stressed about anything. I've worked harder days before and felt fine, but lately all I want to do is sleep.