Hi, Mereja. Soundslike what I have. Skin discoloration like you describe happens with a condition called acanthosis nigricans. I have this (kept scrubbing my neck cause I thought it was dirty) due to PCOS (polycystic ovary syndrome) and high insulin levels. Her headaches might be due to blood sugar levels out of wack throughout the day. Def. something to get checked out - which is sounds like you are doing. More info here:

http://en.wikipedia.org/wiki/Acanthosis_nigricans