Whenever I pin Sust or Prop, I get test flu the following day and it lasts about 2 days. I've had an instance before when pinning Cyp where I went through a vein going in, aspirated, saw nothing and pinned, but my lower back cramped and I shifted my positioning while injecting. Turns out I removed the pin by JUST enough to actually inject some of the Cyp into the penetrated vein and I had the shits and a bitch of a headache alongside a fever for 3 days.
What ester did you pin?