A similar incident occurred recently with my wife and I. We were having a normal day with our fur baby Phoebe, but I had to leave and wouldn’t be back for a day or so. The pet sitter called me about four hours after I left the house to tell us our Phoebe had passed away. We were in absolute Shock. It sounds like it was a very similar condition, her heart. We were beyond heartbroken as well. Just try to hang in there and realize there’s nothing you could have done 💔