Worried I may be pregnant

[Feathers87]

I had sex about nearly a month ago and since I've had cramps in the middle of my stomach with the occasionally stinging feeling in my breasts. I've had them for a good two weeks now and my period isn't due for another week and usually I don't get cramps till about two days before it. I have also been noticing some discharge when I wipe which I never noticed before. It was a clear white colour and then today I noticed a snot like colour discharge when I wiped but there was only a tiny bit. I have also had a small wet patch in my underwear that dries a faint brown colour. I've never noticed any of these before so I was a little concerned. There could be other reasons but any advice would be gratefully appreciated