Please help Save Mustang Mya

I brought home mustang Mya for the 2017 Massachusetts Mustang Makeover and she has not been doing well and quickly declining. She's colicing, won't eat, and she's dehydrated. Mya has only been with me a few days and already is extremely trusting and just wants to be loved. Mya's medical bills have already cost me 1,000 dollars and may increase depending how serious her condition. Any help that you could give would be greatly appreciated.