What to do if I have an unidentified toe fungis. Will athlete's foot cream work effectively on any kind of fungi?

No. Athlete's foot cream will work most of the time. You should treat for more than a month to be sure it is gone. Severe infections may require treatment with an oral medication such as Griseofulvin or fluconazole. If the fungus is in the toenail (tinea unguium) then you will most likely need an oral medication (see your doctor or podiatrist).
Foot Fungus. A fungus is a microscopic plant that can cause disease by growing on human skin. Some people believe that any rash or scaling on their feet or toe nails is a fungus, and this is not true. Anti fungal creams can only work if a real fungus, called a dermatophyte, is present. . You can try an anti fungal cream on your feet, but if it does not work you may need a doctor to get testing and medicine.