We missed it

I am a new nurse I just began my first nursing position this August. I am at about week 5 on the floor and just heard that a patient of mine from the previous week was sent to the ICU pretty much immediately after my preceptor and I handed her off. The story with her is that she was a big lady with chronic back pain and afib who came in with a supra therapeutic INR. she required a TEE with cardioversion and coronary stents. She was given FFP and protamine to ready her for the procedures. I had her two days post cath. She was generally a kind, patient woman who loved to talk and always treated you with a warm smile (even for meds at 5 am). But on this day I walked in and she was gray, not talkative, complaining of some nausea and pain. Her usual Percocet order had expired so I offered her the 650 Tylenol she was ordered and called out to renew her Percocet. The order came in n she said she was not having any relief from her back/abd pain so I gave her Percocet as ordered. Not long after she began to vomit yellow bile. I got her zofran, it stopped the vomiting and she slept for a little while but it didn't help the nausea. I called the PA but he was busy with a code and just gave another order for antiemetic. I was worried about my patient, I took her vital signs, did her HT assessment, there seemed to be no apparent change from the day before accept intractable nausea. Her pressure was lower since her procedures and she did not meet the parameters for her beta blockers, her heart rate which had been in the upper fifties since cardioversion was in the 70s which I attributed to dry heaving and discomfort. She was pale and nauseas but that was it. I had a bad feeling about it though and asked a few senior nurses to look at my patient bc she looked like crap. They seemed mostly unconcerned with the nausea- I asked if it was crazy to call a rapid for something like this because she looked so terrible to me and I just felt something wasnt right- they chuckled. That's the most response I got and the Pa seemed irritated with my calls by about four am. In report my preceptor and the day nurse went on and on about another patient and her heparin drip and the protocol for handoff. I could t get a word in Edgewise about my nauseous patient and my growing concerns. this is how my preceptor and I basically handed her off-Ashen, nauseous and not doing any better than when the shift started. I went home frustrated, feeling like no one listened to a word I said all night, least of all my preceptor and it took hours for me to fall asleep I couldn't stop thinking about her. I came back the next week to hear that she was a rapid response as soon As we left and went to the ICU with an internal bleed from the cath site into her abdomen. The low pressures I had been documenting and telling my preceptor all night with the raised but "normal" hr that went on all night should have tipped me/us but it didn't. I knew something was wrong but I didn't know how to properly express my concern and I felt like I had little support. I am a new nurse and lack confidence and experience and only realize that the tell tale signs were there In hindsight. I feel like my preceptor kind of let me down here and am frustrated 1. That I didn't see what was happening for myself and 2. I had no guidance in how to handle the situation properly and 3. That the day nurse new immediately something was wrong and called the rapid I asked about six hours earlier. I feel terrible. How can I prevent this from happening again and how can I advocate for my patient better in this situation? I'm feeling out of touch with my preceptor and I don't really trust her. What can I do to do better? Thanks for any advice it is very much appreciated.

-newb