Why did my period start off like this?(Girls only please)?

This morning I noticed that when I wiped there was light pink discharge. I usually start off with brown discharge and blood. Why is this? I also usually have slight cramps before I start. I don't really get cramps during my period, only when I get it and when it's ending. I have been taking medication for my acne and acne scars. I'm not sure what it is though. My mom didn't tell me she just said to take it everyday for my acne. My doctor prescribed it to me. On the bottle it did say "Birth control can be altered by other medications" So I'm not sure if it's BC or what. It just comes in this regular orange medicine bottle. Could that have affected it? I'm 16 if it matters and I'm not sexually active in any way so that has nothing to do with it.