It's probably nothing, just train.
My first training injury. I think I did it loading up the weight for DLs. It's a nagging pain that is exaggerated by lying on the left side in bed and if I arch my back, or do a leg raise. Poking around my hip, it seems a bit tender on and above the hip bone at he rear left about 2 inches from my spine, like a bruise. It also seems to radiate through to the front just below my rib cage. I can feel it a bit when I walk, it doesn't stop me walking though.
Don't know if I should rest it, or just go to the gym and see how things play out using only the bar. Any ideas ?
It's probably nothing, just train.
This seems muscular. Maybe the QL? I'd let pain be your guide. Train normally but adjust down if the pain is too great. Just do what you can and assess whether its improving over time