I Took My Birth Control But I Moved On To

I took my birth control but I moved on to my next pack so I wouldn't have my period cause I was going on a trip. I have sex that weekend and the last time I had sex was last week and I have been having symptoms i believe it's been three weeks since I skipped my period. I'm a week before my period and I have a cramps for awhile I have went pee a lot more I feel dizzy I'm warm. It's a week before my period but I been bleeding discharge on and off and it's been really light