What Causes Pain Behind The Neck Along With Nausea?

Hello. My daughter is 20 yrs old, diabetic. Her glucose readings are fine and no ketones. This morning aching in the back of her neck and back of her head woke her up in her bed and she felt nauseous. Has not thrown up at all. Has gone on all day. Pain is now in her lower back, back of neck, coming to front of head and behind her eyes. She says aching is pretty bad although she wouldn t call it severe. It is very present when resting and worse when she moves. She slept a lot all day. Today all she has eaten is chicken soup, an apple and a yogurt tube, water, bit of juice. Temp is 99. No injuries and she has not done any extra physical activities lately. Trying to decide if it is safe to go to sleep and see how she is tomorrow. Thank you.