Cramps...

My period should be coming on 8/22 or 23rd but for a whole week I have had mild and moderate cramps, but also tiredness, gas, sore nipples and so unmotivated... I took a pregnancy test this morning and showed negative... do you guys think is too early? I took a first response and a clear blue but I feel awful and I know PMS are bad but this is worst... is anyone feeling the same?