dachshund skin and allergy problems

[Rosieposie18]

I have a standard doxie. She will soon be eight. When she was around four she started having allergy problems. Now that she is older she is much worse. We started her on allergy shots almost a year ago now, but they don't seem to be helping her. She constantly licks her hocks and armpits. Also she has a bad odor, and we have to bathe her every two days. The skin on her belly and armpits is very dark, and she secreats an oily substance from her skin. I was wondering if any other doxie owners had this problem with thier dogs? I would appreciate any feedback.