Irregular spotting?

Tina
Hi. I've been trying to conceive unsuccessfully for 4 years now I am due my period in 13 days but a couple of days ago I noticed a little bit of spotting when I wiped it was a very light pink in colour and not very much at all since then every time I have wiped there has been spotting some times not very much other times quite a bit. The colour changes from anywhere between light pink to a dark browny colour. I've also noticed it in the lining of my underwear a few times. I'm not getting any discomfort although I have been feeling a little hungrier and sleepier than usual and sometimes a little sick. My period is never early and if anything sometimes a little late and normally accompanied by very painful cramping that starts a few days before which I haven't had yet so doubt that this is the start of my period. I was just wondering if anyone else has experienced anything else like this or knows what it could be. Any advice would be appreciated x