The most common symptom of cervical cancer is bleeding from the vagina at other times than when you are having a period. You may have bleeding
 

Between periods 

After or during sex 

At any time if you are past your menopause

 

Some women also have
 

A vaginal discharge that smells unpleasant 

Discomfort or pain during sex

 

Doctors call pain related to sex 'dyspareunia'.  There are many other conditions that cause these symptoms.  Most of them are much more common than cervical cancer.  But you should go to your doctor straight away if you have any of these symptoms.  You probably don't have cancer.  But if you do, the sooner you are treated, the more likely you are to be cured and usually the less treatment you will need to have.

Pre-cancerous cell changes do not usually have any symptoms.  Which is why it is so important to have a regular smear test.