Please Help/Period Question

Sort of a TMI back story to help answer my question, sorry but here we go. I was supposed to start my period around today but I started to get brown blood yesterday and it started off as spotting and I still have it today. It's been 24hours since I started spotting brown blood and I'm really worried because I don't have sore breasts or any sort of cramping that I usually do with my period. Every time I usually start my period, it's always a rich red color but this time (if it is the beginning of my period) it's brown. I'm worried it could be implantation bleeding although it's a small chance. Some factors that may have led to this would be: I smoke a couple times a week, last week I had protected

sex but he didn't even finish (it was my first time and he only got the tip in so) I eat fairly healthy maybe some sugar here and there for sure though. I'm 5'6" and weigh 170. Please give feed back on what it could be, thanks so much