Vaginal discharge is not only normal but is necessary for women. The discharge will change consistency during the normal cycle and is dependent on hormone levels. The very thin, almost clear, stringy discharge is known as spinbarkite. The mucus of the vagina thins out like this about 7 days prior to ovulation. This thinning of the mucus allows sperm to swim through the mucus to the cervix and allow fertalization of the egg to occur. Once ovulation is over the mucus thickens again and may have a clumpy texture. This will prevent any sperm at this point to enter the cervix. Following this you will get your period. All of this is normal.
A yeast infection will be white discharge that has a cottage cheese consistency. It will cause the labia to itch. Burning during urination is common white a yeast infection. There may be a slight odor with a yeast infection. Monostat is an over the counter preparation to treat a yeast infection.
Any discolored or foul smelling discharge warrants a trip to the gynecologist. This is could be the signs of an infection. Waiting for discolored or foul smelling discharge to go away spontaneously on its own is not good and potentially dangerous. It can lead to a more serious infection that ascends into the pelvis.
When in doubt see your doctor. Good luck.