Doctors have different ways of approaching this problem. Taping, ice, anti-inflammatory medications both over the counter and prescription, rest, stretching, pre-fabricated arch supports, custom made arch supports, night splints, steroid injections are some conservative treatments. Surgical treatments are many as well.
Just because one doctor recommended a cast, does not mean it will or will not work. You should have a detailed discussion with your doctor and have a clear understanding of why a certain treatment is being done.