Put horse to sleep on Sunday?

On Tuesday I noticed my horse did not eat at all and looked sick, she had her head low, barely wanted to move, and kept looking back at her stomach. I knew she must of had a mild colic and called the vet. When he showed up, he gave her benamine, checked her mouth and examined her all over, but could not find anything else wrong with her. It is now Friday, and my horse still refuses to eat and drink on her own, but she seems fine. She wants to run around in the arena, be handwalked, and lastnight I was up there force feeding her applesauce & gatorade with a syring, and she did not put up a huge fight. It seemed as if she actually enjoyed me feeding it to her. My real question is, if she does not start eating and drinking on her own by Sunday morning I was going to call the vet to come out that day to put her to sleep. I hate seeing that she is not eating and drinking, but it baffles me because she looks and acts like a healthy horse. Mind you she is in her 30's and she is Arab/quarter.