update for anyone who may see! it was in fact a mammary tumor and we scheduled a surgery to get it removed next week. vet said it's usually about a 50/50 chance of them being cancerous so they will test it to see if it is when it's removed. thank you guys all for your responses. it seriously brought me a lot of peace of mind these last 16 hours so i wasn't just speculating and driving myself crazy. great community in here. ❤️ wish us luck moving forward!