I'm not sure Helen! I can totally appreciate you'd be feeling a little worried. I'd give the HPH a ring and speak to one of the midwives - they should be able to help you (I know I rang them during my PG with Jacob a few times!).

I had BH with Jacob that started at around 20w but they weren't painful - just uncomfortable and tight IYKWIM? They only started to get painful right towards the end.