feeling so discouraged

I have worked the past three years in the ER. I recently accepted a float position in a hospital in NY. I lasted 2 months. I got 3 weeks orientation on one particular unit, the so-called toughest unit in the hospital. I survived, the assistant manager even asked me to consider joining them permenantly. I got three days on another unit. Survived that. Then I got one day each on three other units. Some were telemetry, some were not. My first day off of orientation, I went to a unit that I had not been to before. It was fast, I was bombarded by family members and stayed late to complete charting. We have 7 patients in NY. My second day, I went to a non-tele floor. I had not been to this particular unit before either. I had determined I would not be there late charting again, so, I assessed, passed meds, and charted assessments as I went. I got to my third patient that morning and was making good time. A cardiologist showed up to assess this 95 yo lady, she was not on tele, she was over the top anxious and hx of bipolar diagnosis. The Cardiologist no sooner than turned on his heel and left than she was calling after him. She yelled, "I'm having Chest Pain." I did not know this floor had a policy that when someone says the magic words, they call an RRT. I assessed her, no SOB, no overt sign discomfort, no diaphoresis, no SOB. I suspected she was being manipulative to get the Cardiologist back. I had been warned about her by the NOC nurse that she yelled out constantly. I paged the Cardiologist. A couple of minutes later, the Charge Nurse approached me and asked why I had not called an RRT. (In the ED we are the RRT). I told her I had paged the Cardiologist and did not know I had to call an RRT. She had described her pain to me as a breathing pain. Because she was yelling full voice and LS were clear, I didn't have a sense of urgency. Long story short, RRT was called. Cardiac event ruled out. I was on notice for not following the policy of this floor. The Manager of the floor demanded that I be put back on orientation and spend two days on her floor as an orientee before coming back (but I did finish out that day on my own). My next working day I went to a unit where I had prior orientation. It was stressful, but no issues. Then, on Monday, I returned to the Med Surg unit for orientation. My guard was down because, I felt I would be shown the ropes. I got assigned four patients and was working on my own with a resource. At 11:00 I discovered I had missed someone's 0800 medication. I reporte my error. I called the MD. I got a stat order to give the overlooked medication. I handed the omission report over to the Manager and was met with grave disdain. Later that same day, I could not find a patient's insulin. I requested from Pharmacy and went about my business. An hour later, the insulin wasn't there and I contacted the Pharmacy. They immediately sent the insulin. This particular patient was NPO. Her BS was 153 and the sliding scale started at 150. I marked the 11 am dose as "not given" and intended to re-check her BS to see if she even needed 2 units at that time. I informed my Preceptor. To my astonishment, he reacted as if I had injured this patient. He went to the Manager to inform her I had now two medication omissions. I was sent home. I was fired the next day. They cited the above reasons and stated my "critical thinking" did not match my background. My head is still spinning. I have never caused patient harm. I have never had my license investigated. I've been a nurse for 13 years. And lastly, in applying for a new job, I just found out a former Charge that I have been using as a reference for a couple of years now gave me a bad reference. The agency I'm trying to sign up with told me she had, "in no uncertain terms" not recommended me. She has not returned my gentle request to give me feedback. I feel right now like I've been thrown from a horse and kicked. I have recent letters and evaluations from recent contracts that support me as a nurse. I feel I am a strong nurse and competent and compassionate and spend the time educating at BS...and I do so much that goes unrecognized....like sooo many of us do. Can someone say something to help me put this to rest? I am so discouraged with nursing and Administration and nurses who have no problem throwing another nurse under the bus. I'm feeling a little sick from this profession.