A 25-year-old woman presents with fatigue, generalised aches, and difficulty concentrating for the past 6 months. She reports waking up feeling unrefreshed. There are no specific joint swellings or neurological signs. Examination reveals multiple tender points over the neck, shoulders, back, and hips. Routine blood tests including FBC, ESR, CRP, U&Es, LFTs, TFTs, and coeliac screen are all normal. What is the most likely diagnosis?