My 7 year old Chow Has had two strange heat cycles 8 months apart. They are heavy in flow and a chocolate milk looking discharge with a terrible odor. Today is the two week mark and she appaers to be "worn out" she want to sleep all day and isn't eating. She does drink alot and is going to the bathroom regularly. Her heats were very irregular all her life, sometimes going two or three years without one. Is this normal for older dogs? or should I be concerned?