patch advice please!

I've been on the patch for about a year never had any problems until the other day my patch fell off and I didn't realise until the next night around 11 at night. I had unprecedented sex the day before is there any chance I could be pregnant? I'm having brown spot bleeding on and off also feel very tired and sick and getting a lot of cramps I'm not due my patch free week until next Wednesday I'm really scared and confused.