Hold on, don't give her the cull cow ride just yet. I have a heifer that was standing yeasterday that is safe w/ calf. Bred or not maybe changes in the weather may have something to do with it. This is the second time she has had all the signs of being in heat, had her preg checked this morning. Safe with salf to my AI date, May 3rd.
As for the swelling infront of her udder, she could be comming to milk. The best way to know is to preg check. When was the first time you saw the bull ride her? When did she calve last year? Does she have adequate mineral?