If I remember correctly, this is your first cycle correct?
What Gauge are you using?, how long of a needle and how far did you go in? Until your muscles get used to a foreign matter tearing apart the fibers, then you're gonna have pain, virgin muscle pain. Anywhere you pin, you're gonna get that till you get into your cycle a ways, or 2nd cycle. Oh and go SLOW when injecting to help with pain too.
As far as the blood goes, you probably nicked a vein going in. As long as no blood came in to the syringe when you aspirated then you'll be fine. I always pin quads and always aspirate. I use 27g 1.25" and go in about in 1". Once I started being consistent with the distance in, the virgin muscle pain stopped happening so much. Also, when I'm pinning, if its sensitive when the needle touches my skin, I move to another area I cleaned with the alcohol pad. Wednesday was the first time in 2 cycles I've felt something hard in my quad to push through, tried and it hurt like a bitch too, it was about 1/2" in, pulled the needle out, changed needles and injected in another area.
All just learning curves friend.