I do think it was lash egg material, but I hate to disagree with your vet, since I am not one. I would have continued the amoxicillin and finish it, since tylosin is more for treating MG respiratory infection or sometimes used with enteritis. That said, some people don’t like to use antibiotics for lash eggs or salpingitis, since it may or may not help. Lash eggs may look different in each case. Some look flesh colored, and may have a cooked egg appearance inside when cut in half. But here is a reddish one that is a little more like the one yours had:
https://www.timbercreekfarmer.com/w...5/11121404_10155527529995702_1083264752_n.jpg