Update: Our dear horse Simi came back from the hospital and the result of his MRI is that he has fluid in his navicular bones in his front hooves and bruises in his heel bulbs from low heels. So the treatment is to inject him with OsPhos, an osteoporosis drug, to help solidify the bone and stop any further changes from happening plus trim back Simi's toes and cast his hooves on wooden blocks and squishy pads to give him a comfortable cushion while his heels are growing out. Fingers crossed the treatments will work and he will become comfortable enough again to be ridden happily!