does anyone have answers for me?

So My period is about 4 almost 5 weeks late but I did hav slight dark but very little bleeding for less then a day a few weeks ago and I took a pregnancy test and it was negative idk what's going on I'm having some cramping and gas and frequent peeing. Has this happened to anyone else? Any ideas of what's going on? I hav a doc appointment soon just wanted to reach out and c if anyone knew what's was happening.