A lot of brown discharge???

So I started the pill about a month ago, and I've had alotttt of brown discharge of the past two weeks like I've even had to wear a pad because I'm sick of ruining so many pairs of underwear, if it helps I though I would see what it's like to skip my period, so when I got up to the bigger pills in my pack I went onto a new pack and took the next active pill I think it is instead of the one that makes my period come, can someone tell me why I'm having this brown discharge and what I can do to stop it :(((((