I would see a doctor or a dermatologist for both of you. It might be some kind of skin infection.
May I ask what ethnicity you are as that may make a differance in pigment, could they be any kind of bruising on the child does she jump around and maybe bump her hips and legs as they do on a trampoline , with you a possible skin allergy condition check out any gels , lotions you use, .We have a dermatology forum on Med Help they may know more about this condition and as always ask your Doctor for information about it . Good luck to you