Nipple pain

My daughter is 13 months old today and hasn’t been BF since she was 4 months old. For the past 5 months my nipples start to tingle and ache like I need to let down. I’ve tried hand expressing to see if I could get any milk out (I didn’t) to rid of this annoying feeling but it won’t go away. My nipples are also still dark like they were when I was BF. Any ideas on why or what I could do?