Group B streptococcus

I just found out that my GBS test came back positive this is my fourth child and all my previous pregnancies were all negative so I guess I am asking how all of a sudden can I be positive for GBS when I have had the same partner for over six years and my first three pregnancies were all negative? Pleases help me out here. My Doctor says not to worry they will give me antibiotics when I am in labor but after reading other stories of parents that have had it I am really nervous and stressing out here. I just don't get how all of a sudden I have GBS.

[Victoria01]

GBS is a common bacteria found in the vagina of up to 60% of women. There are usually no symptoms and it's a normal bacteria. It can come and go and is NOT sexually transmitted. You can test positive one month and not another, but they will give you antibiotics just in case since you have tested positive. Usually, there are 2 doses four hours apart during labor. There is nothing to worry about, as it is quite common.

[cocacolapanda]

Also, I had the IV and it was horrible!  I was also told there's a pill you can take too.  I'm asking about it this time, as I hate to be hooked up to an IV.