Tired

I'm 3 months post partum and since about 2 months pp I have been so tired and just feeling off. It's not a sleep tired, because my son only wakes up once at night and it doesnt feel like a sleep tired. I usually feel super worn down and tired around 3 or 4pm. Some days I feel shaky and dizzy even when I'm sitting down. I eat healthy and drink a gallon of water a day. I'm also not breast feeding

I have an appointment next week to get some blood work done and discuss it with my doctor. I'm just wondering if anyone else has ever felt like this?