Glad she is eating again. I see her empty feed bowl in her stall there atm
You could possibly speak to your vet about gestational laminitis. I have had a mare here that i had to cut the protein/sugars from her feed for her last 3 months of pregnancy because she got real sore. No heat or anything in her feet, and she wasnt even overly heavy. It can be caused by a few things in late pregnancy - obviously increased weight gain being one of them, but also the hormones relaxing the tendons/coronary band etc which in turn can allow movement = inflamation = laminitis. Also, it can be caused by a uterine or placental infection or thickened placenta, which after an ultrasound, was what we discovered was the cause of my little mares case. She went on antibiotics to clear the infection and ensure the foal didnt get infected and become sickly. We also put her on regumate, as at that time she was only 9months along, and was starting to bag up, so we were worried about abortion (which can also happen with placental infections).
I dont mean to worry you, it could be something as simple as giving her some pain relief, but if she keeps up the being miserable, and so sore, then i would at least mention it to your vet and get his opionion on it
With Darla, it could be a simple cause, like your upping her feed recently to increase her weight gain. She may just need a little less protein to help her along (which wont help the weight gain, but should help the feet).