I am not a Dr...but my wife is. Huge difference in IM vs SubQ. Unless you're doing daily injections, SubQ is NOT the answer.
It's specifically IM.....for a reason. I can ask Why when she gets home. But she oversaw me for years. Always IM. If SubQ was an option or better, for sure she would have told me.
Soreness: You are doing something wrong. Should not be sore at all. Even immediately after. Going through a Nerve will be sore. You'll feel it immediately. But even after, it's not going to be keeping you awake.