eeeeek i hate when the doctor checks my cervix it hurts so bad either that or im just a big baby..... if you're really worried about it if I were you i'd just schedule with your baby doctor and have him check your cervix for you to ease your mind
it's common for women who've had babies to be a fingertip dilated throughout their pregnancies, simply because everything's not quite as tight as it once was, not to worry. And as long as your hands are clean there is no problem with you putting your hand/fingers in there, after all your husband sticks his penis in there which is often less clean than a freshly washed hand.