I have been taking contraceptive pills for 4 monthes, this month I still have four more pills . Yesterday and today I have been having brown discharge and a brown sticky substances! Is that something to worry about? Please advice me

I get it all the time, usually if I skip the break between my pills.
It's old blood that didn't come out from your last period, I don't know the reason but it's not uncommon. If you're worried go see your GP about it, they'll explain it better.