Are you sure there is nothing in the barn she could be getting into? Lead paint for example? They will mouth and suck on everything at that age. Whenever I have had to hold a calf in a building without safe pens, I would make a pen out of hay bales, so the only thing they could chew on would be hay. I am usually able to get an extra like a twin onto another cow before too long. If I can't, I will move them outside into a pen once they are as old as yours and make a wind break out of bales. I have a hay shed with only a roof, although the sides are open. If I did not have a roof, I would probably put a piece of plywood over hay bales to make a three sided covered wind break.
It is not too late to get her on another cow, if you have one lose a calf. I have convinced a cow who lost her month old calf to take one of the spares. It took about 10 days of penning her for forced feedings, but it worked. Last year the last cow to calve had one coming with both feet back. We noticed too late, and by the time we caught her and pulled it, the calf had died. We had a 6 week old twin we were bottle feeding, so we took the dead calf away before she could see it and rubbed the afterbirth all over that 6 week calf. The cow took it instantly, but the calf was a little afraid. We got the cow in the head gate and helped the calf suck. I had been feeding the calf with a bucket before that and was a little worried she would not quickly pick up on sucking a nipple again. By morning those two were paired up and that calf did great. We had been having some issues with her scouring and going off the bottle before that, but the cow cleared up all problems and she ended up catching up to her twin in weaning weight. That would never have happened otherwise.
