PIO question

Please bare with me... I'm a paranoid and slighlty crazy.

My DH has been doing my PIO shots. He had to go out of town so yesterday he taught my mom how to do it.  She's given shots before to people so she felt comfortable doing it.   So, she came over this morning and did it... and honestly I didn't even feel the needle go in at all this time... she said she felt like she hit mucsle and that it went in slowly.  Now the injection site is burning a bit... and feels different from all the other shots I've had.

Has that happened to any of you guys?? a shot that burned?? Do you think it's just because the area is starting to get sore from the shots??   My fear is I've got too much junk in the trunk and that needle isn't long enough to hit muscle. (I did mention I'm paranoid, ;)  LOL)

I just want to be sure to do everything right!!   Progesterone blood test in the morning...