Is there anything that can effect your labour?!?

I'm 26 weeks pregnant and now i know boils are perfectly normal due to hormones and as are skin tags, but why do we get these?! and how do i explain to my doctor about them? it's easy to talk on here as you can almost hide, but i'm only 20 years old and i feel really embarred :o( & i am absolutely petrified about having my Anti D injection because i'm rhesus negative, i'm just scared really because i'm a newly single mum to be and i haven't got that extra back up from a partner and stuff - advice anyone?