may be the way to go. The 911 has antibodies in it and the DDA has mycotoxin binder. Both are good probiotics.
I didn't think Safe Choice was for growing horses? If you are looking for a low or no grain feed, check out Triple Crown. I give my younguns either Triple Crown Senior or Ultium. Be sure to give at least 6 pounds daily of the Triple Crown per the label. My colt is on DDA, Calm-B, and Colt Grower. Once I move him to Fl he will go on 911 and switch to Ultium feed then back to DDA. Then in Nov I will put him on Breeder's Choice in prep for the breeding shed.
If she stressed during the weaning period she may have an ulcer. The 911 helps out with those.
I would cut out the mineral oil - it can loosen the stool in of itself.