I used to have heightened and fantasy worries about HIV and went through a very similar situation. I had to get some counselling for ocd and anxiety.
You had no risk.
If you have ever been to the doctor and had a needle injection then you know what they feel like. If your not sure, then the for sure it was not an injection you were given.
Why would a construction worker that walked by you inject you with and HIV blood infected needle and where would he get this hiv blood filled needle?
You mention you have ocd so maybe post your fears in the ocd forum for help.