I had the same issues a few weeks ago. In both quads. My right leg was first and it took about 7/8 days for the intense pain to go away. Which happened to be the same day I injected again in the left leg. It too took 7/8 days for the intense pain to go away.
The next injection in my right leg, I measured one full hand down from my waist/belly (sitting on a chair naturally) and injected there and in the outer (top) part of the quad. Went in smoothly and no pain whatsoever. So, I recommend trying that, no PIP or the intense pain I felt the previous two weeks.
Also, not that this will help, unless you want to move the injection site… I read on another form and I witnessed it myself… the harder it is to inject the oil in, the more it’s going to hurt. If it goes in easily, the less it will hurt. My previous two injections, with a 1" 25G needle, it took what seemed to be a long time to go in. (About halfway down the quad on top (the thicket meaty part.))
When I measured down as I explained earlier, it went in easily and what seemed to be about 10-15 seconds compared to what seems 25-30 seconds. Your mileage may very but I’d try it.
EDIT: My first injection was 500mg (2cc of Enanthate 250) in the right leg and my second injection was 250mg (1cc of Enanthate 250) in the left leg. Using the same exact vial of Enanthate, I had no issues once I measured it a hands width down from my waist/belly.