The short answer is that an employer can pay you whatever hourly rate they want to pay so long as it is minimum wage or above. They do not have to have a reason to do so and there is nothing you can do to stop them. Welcome to Michigan "Right to Work at will employment." Unless you have a written contract for employment or belong to a union, your employer has exclusive control over your pay, hours, and working conditions. The exception to this is that the employer cannot alter the terms and conditions of your employment because of your race, gender, national origin, age, etc. Its a sad, sad situation, but until we eliminate 'right to work', I foresee things getting even worse.
Each employment situation has unique facts and circumstances. This means that information and advice cannot be taken literally and should be used as only informational. The information provided here is not legal advice and should not be interpreted as such.