You said you've had it since week 8--have you mentioned it to your doctor? I had what sounds like the same thing and my doctor wasn't real concerned, but I wouldn't just ignore it if it's bothering you. I've learned so far in this pregnancy that it's better to get something checked out than to make yourself crazy with worry.
Anyway, the doctor can check the amniotic fluid levels with an ultrasound. I know I felt so much better when mine told me the fluid levels were good.
Sorry I wasn't much help. I'd call and run it past your doctor. If he/she wants to see you before your Nov. appointment, they'll tell you.