Why has having my blood taken suddenly started to affect me?

Although I have fainted a few times in the past, I have never had a problem when getting blood tests done. I have never even had an issue with blood, I worked in a hospital theatre for some time so saw operations with no issue.

However last week when I went for a blood test the nurse was taking quite a while and had to switch arms. She kept asking if I was ok and it was at this point I started to question myself if I was ok.. I started to overthink and freak myself out, suddenly I felt a sense of doom and my vision started going. She let me lye down for a bit and brought in an assistant to distract/talk to me. I didn’t really want all of this as I felt I needed quiet and for her to just get on with it. The more I was questioned if I was ok the worse I felt. I don’t think it was the blood. In the past I swear my fainting episodes have been caused by overthinking etc.

Anyway I had a phone call to say that I had to get them done again as they couldn’t be analysed due to the sample (for some reason). I have to go tomorrow and am terrified of overthinking and fainting.

When I do faint it triggers my anxiety for weeks I keep worrying that I will faint.

I am thinking of just abandoning the blood tests, I don’t know why it has suddenly started to affect me

I am honestly the biggest wimp in the UK at the moment due to my anxiety.