If you've had a positive test, but 2 negative ones since then and you're cramping then I would suggest seeing your doctor for a blood test to determine whether or not your hCG levels are rising or not. Vaginal discharge is normal in pregnancy, but the tests turning negative might not be, so best to get those blood tests done.
It sounds like normal vaginal discharge but did you read the first test within the amount of time it said?!? It is always best to take the test in the morning as your first morning urine is the most concentrated.