The pain down there is from the pressure off the baby, its nothing to worry about

My midwife was explaining all this to me only this morning actually.
My baby's head is engaged now *woop*

and she said that those shooting pains are gonna become more frequent but its nothing serious. If its unbearable you should phone your doctor though, just to put your mind at rest if nothing else.
BH's as Jenny said just feel like your tummy is tightening, I get slight pains across my bump aswell like achey pains.