Any sudden change to your discharge may indicate a vaginal infection. You should be aware of how your discharge naturally varies throughout your cycle and what isn't normal, but obvious warning signs of infection are:
a change in colour or consistency
a sudden bad smell
an unusually large amount of discharge
another symptom alongside the discharge, such as itching outside your vagina or pain in your pelvis or tummy
unexpected bleeding from the vagina
If you're not sure whether your discharge is normal and are worried about it, consult Gynecologist...