Allergy or physical ailment?????

Question
I have a female "doxie", who has, what seems to be an allergic reaction. Constantly scratching her underside & licking her feet. She gets treated with Advantage, as prescribed. She has developed "bumps" or rash on belly. But what is disturbing is, on her hind feet there is loose skin draping over her little "heels". Her fur growth is disrupted in these areas. She appears to eat fairly well, but is thinner than a few months ago. I have 2 other  dachhunds, a pekinese, & have recently obtained a yorkie. The itching has gone on for about a year, now but the loose skin has appeared the last 6 months. "Solo" is about 12 years old now, not spayed, & very active.  

Answer
It sounds like a food allergy and I would recommend trying a hypoallergenic fish-based diet such as those made by Verus, Wellness or Flint River Ranch.  The bumps and rash you describe is a secondary skin infection,  and she should be treated with antibiotics for AT LEAST one month.  Most likely she also has a secondary yeast infection on her skin from the constant licking...this should be treated with anti-fungals such as Ketoconazole.  In addition, something should be prescribed to slow down the itching...at minimum you could try Benadryl (1 mg per pound of weight 3 times daily).  As far as the loose skin, that is probably from the weight loss and often times these little guys do have extra skin at their back feet and that is not going to go away.