Well if its itching out burning or smells then its an infection but its very normal for discharge to increase especially late in pregnancy also it should be milky and white, yellow could be infection but if its clear and watery you should get checked out because that could be a leak in your amniotic sac, very bad at 30 wks
If you get a sudden increase in discharge or change in discharge it's always best to get it checked, it could be an infection.