Toddler complaining of back pain

My daughter is a couple months away from being 3. Yesterday in her car seat she said her back hurt and then was fine after that. This morning she came in the kitchen while I was cooking and touched her back and said “ow my back hurts” then went back to playing with her toys? She hasn’t done anything to hurt it that I know of.

Should I be concerned? She also has bags under her eyes & the past couple of weeks she says she’s tired around lunch time but refuses a nap. Just wants to keep playing with her toys. She stopped napping around 2 and I’m wondering if maybe she needs to start again? Anyone else in the same boat? Also, she does not eat or drink dairy. She had a peanut allergy and we are unsure about the dairy so we just don’t give it to her (she has appointment January with allergist.) maybe vitamin deficiency? Just wondering if anyone else has had the same issues.