Hi Farmer_Neal,
Others are spot on about vitamin and mineral shortages in the diet you're feeding. Though I'm not anywhere near being an expert I'll just explain what (to my reading) is missing. Several of these shortages can and will produce exactly the symptoms you're seeing.
Unless they're outside on pasture eating insects and accessing sunshine they're probably missing vitamins D (which helps them absorb calcium), K, and vital B vitamins from microbes like yeast or lactobacilli. Soybean feeding tends to deplete minerals so it's a fair bet their mineral (particularly calcium and phosphorus) levels are too low as well. The leg/foot problems you're seeing now may be rickets.
It's not too difficult to find additives that balance out what you're feeding, but there's a bit of reading to do. Old1940s poultry books can be great places to start. You won't save money feeding a home ration but it's quite satisfying to do it and when properly formulated the birds will never be healthier.
Best wishes,
Erica