I tried to post last night but got locked up and it did not save. I too had the cording, my surgeon said it is called Mondor's syndrome. I had it twice, first time was in my side/ abdomen. My PCP had no idea what it was and I was going to see a vascular doc, when my surgeon told me what it was. Luckily i cancelled the vascular appt though. The second time I had it you could see it run down my arm and I could feel the pulling down my hand, but the vein was visible in my armpit and part way down. I have not had it since.
As for the phobia, welcome to life after cancer! Yes, you will get a little less phobic, but you will also better learn how to handle the anxiety and manage the concerns. In my opinion, this is just about the hardest part, is learning to live comfortably after cancer. Only those of us here can relate, not our families or friends. They just think we should be happy it is over, not getting that it is never really over.
Be careful not to use the onc in place of a PCP, but I would keep him apprised of new symptoms or concerns. Mention the back and elbow to him and ask if you should take those concerns to your PCP instead. If he thinks it is cancer related, he can intervene. At U of M, they tend to not scan unless there are symptoms that sound like they could be cancer-related. In over 5 years, I had a bone scan once and a chest CT only because I was having a pain in my sternum that was chronic, and it needed to be evaluated (turned out to be arthritic changes from radiation).
Hang in there...it will get better, slowly but surely!