I have very irregular cycles. I never know when to expect my period. Occasionally I will see light pink on a tissue and then nothing will happen for weeks. It may be irritation. Today I saw pink on the tissue and drop of blood in the toilet. There was no stain anywhere else. What do I do?
Small stains found randomly on a tissue after wiping will not render you a niddah. In the toilet if it is a tiny amount [like a penny] it will also not make you a niddah. If you see a larger amount in the toilet, you should consult with a Rav.
In general such small staining could be pretty much ignored. However if there were a few stains close to evening time you should refrain from relations that night to avoid problems. In general you should be more careful when you start to feel other symptoms that signal for you the imminent onset of your period.