So about three weeks ago, one of my Boer does started limping on one front leg for no apparent reason. Since then, the other doe I have in the same pen has started limping on the same leg. I also have a wether in with them, and all three of them in the past week have started to lay down constantly, even while eating. They all are eating and drinking, and seem to be perfectly fine otherwise. There is no heat in their legs, nothing seems to be abnormal, and their hooves are fine. The knees of the legs that both does are limping on do seem to be slightly swollen, but it's honestly only noticeable if you really look hard. What could be the problem? My mom seems to think that it might be because they are not in a very large area (we're in the process of building a new pasture), so they aren't getting much exercise. Even before this happened, they really didn't do much unless I walked them. I have penicillin, should I just try giving them that for a while and see if it helps?