What Causes Light Periods, Back Aches, Stomach Cramps And Headaches?

Hi, I had a very light to nothing period 2 weeks ago this is unusual for me. I have since been getting lower back aches, stomach cramps and headaches. I am not on any birth control and am 32 years old. The home pregnancy test came up negative, should I go to see my gp or leave it until my next period is due?