My dog ped away 4 days ago, had taken her to emergency vet?

I am a wreck over the loss of my 11 yr old schipperke. She was my best friend. i am so confused as to the events over the last 3week prior, She was having breathing problems about 3 weeks ago. I took her to emergency vet, and they did xrays blood work etc. and told me she was having indegestion,and gave me enzymes. Last Sat it was worse, she started breathing heavy and looked very scared i took her to my regular vet and within 5 min told me she had a huge m on her liver.(Cancer) and was bleeding out.. within an hour she died in my arms. i will never forget this. WHY DID THE EMERGENCY VET TELL ME SHE WAS IN PERFECT HEALTH. Should the xray and bloodwork showed this. The second vet says yes they should have. Please be kind when responding,, Thank you