Simple, use whole cows milk. No improperly mixing formula from that.
But first, clear up the scours. Use a clear liquid diet. Though if could be the diseases mentioned. What color is the scours? What does it look like (bloody, frothy, etc.).
In the medical field, when a nurse gives report, it is recommended to give an incredibly descriptive report. If you can basically see and smell what the person is describing, it is a good report. Sure, we don't want to hear/smell a GI bleed in words (since the stench and appearance is freaking awful), but it goes a long way to knowing the condition. Just one example. FYI, yea, GI bleeds, yuck.