yeah, the pain is real bad! my suggestion to you is just start off with getting one bottle. don't load up for a whole month's supply cuz you may decide it's not worth it and will have a shit load of lutalyse left over that you won't use.
it feels like the worst charlie horse you've ever gotten and worse. have quick access to the bathroom when you inject. start off with no more than .5cc in a muscle, but preferrably less, .25cc.
or if you're lucky you'll react like happyscrappy and not feel a thing lol. but that's rare.