It sounds like your dog might have a skin dermatitis such as yeast or staph dermatitis. Staph usually occurs on the lower regions of your pet and tends to have small pimple type bumps. Shampoo containing Chlorhexiderm and/or Oatmeal can help with this condition though it does not cure the allergy. Yeast typically shows as a greasy area that has a sweet musty odor. Sometimes the skin can become inflamed, darker and thickened due to itching. Yeast likes areas such as between toes, armpits and ears. Selsun Blue Shampoo can help with Yeast dermatitis. When shampooing, lather and leave on 15 minutes before rinsing. These shampoos are not meant to be a cure, just a relief until your pet can see a Vet.
Since allergies are frequently the cause of skin issues, you might want to read up on allergies on the following sites.
The growth if inside the mouth might be Canine Oral Papilloma. It is a viral wart. Dogs get them on their lips and chins normally but they can be found between the toes as well. It usually clears up on its own in a few weeks. You can read more about this here:
If not, it might be a common wart or growth. A lump or growth is hard to diagnose even with an office visit, over the internet it is even harder as we can not even see the growth. A lump may indicate cancer, but many such growths are harmless. Many lumps are not painful or bothersome. It may be a fatty tissue deposit called Lipomas or a wart or a hematoma, but to be positive your vet will need to test the lump to be sure.
Any lump found on your animal should be tested to determine if it is a cancerous or benign lump. Your vet will want to perform a fine-needle aspiration or other appropriate test. It is performed quickly and allows some of the cells of the lump to be evaluated by the veterinary pathologist. This test will allow the vet to determine the nature of the lump and take the necessary steps to remove it. Some vets will leave it alone if it is not serious. If it is an abscess, he may just drain it and prescribe antibiotics. Lumps that are solid feeling, feel attached and fast growing should be checked as soon as possible as these are the ones that are more likely to be serious.
Here are a few sites for additional information and pictures to allow you to get an idea based on the physical characteristics..
Picture of Lipoma
Picture of Hemangiosarcoma
Picture of a mast cell tumor
(mast tumor site)
Hope this helps.