maintaining calm (trying)

This morning walking Mabel I picked her up because she was being a stubborn girl. I felt a large lump on her lower belly. She has had a fatty tumor in that spot for over a year, checked by the vet and very common in dogs. It was, however, firmer and larger than before, although I check it at least once a week. I freaked, and we ran to the vet a few blocks away. I was panicked. The vet checked her and said she needs to biopsy it, but that fatty tumors can change suddenly and become firmer. After examining it she is almost sure that is what it is. I trust her and I am trying not to worry. We will curtail our trip, and return from Vermont on Wednesday rather than Saturday.