Confused as to what these cramps are?

been trying to conceive for about 5 months now and been taking pregnacare, bn having regular periods, normally 27th or 28th of month. this month however i had what i believed to be my period only it was lighter in colour and not a constant flow as usual but only like apparent after going to the toilet and wiping, that was last week, now this week, yesterday and today I have been having what can only be described as period pains, only no period in sight, like a cramp in my lower right side, what is this? any ideas?