Definitely not your waterbag! Just some discharge which is perfectly normal. If it's your waterbag it will keep on leaking and soak your pad. Tummy cramps if it feels like pulling then it's your ligament stretching which is also common in pregnancy or it can also be braxton hicks since you're in the 3rd tri already. As long as the cramps are mild and bearable then there's nothing to worry about! Unless it's painful then go to the hospital asap