Shooting in your thin is NOT recommended. The thin is to thick to have any positive effect.
The needle probably didn't "clog". It may have been a number of things. You didn't get a straight down push on the plunger so it didn't shoot in easily, you inserted the needle and the hole was on a muscle fiber so shooting it wasn't as easy, etc etc. My advice would be to try your thigh again. It's my favorite place to shoot.