She smells.... how am I supposed to tell her that with out hurting her feelings?

so my mom and i were packing today and i noticed a terrible smell i left the room to go check if it was me and it wasn't... i walked back in and said "what's tht smell?" she smiles and says "i dont smell anything hun.. maybe its one of ur brothers old diapers?" i shrugged and went back to packing the smell keep getting stronger and stronger... then finally it hit me... i walked past my mom and stop right behind her... it was her.. i love my mom to death but she really smelt like B.O. and fish (sorry mom) how am i supposed to tell her tht she smells really bad without hurting her feelings... or should i just live with the stench??