US PASSPORT HOLDER travelling from Philippines back to the United Srates

I have a valid US passport good til next August 2017, I booked my ticket online from Philippines to United States, my layover was inconveniently changed from 3 hours to 99 hours in Shanghai, China in between flights. Whats steps I must do if I can't get my flight changed back to my original 3 hour layover? How much will it cost and how long will the process take?

Take note that the Philippines is a very slow moving economy.