I have been on the recieving end and done a lot of research on discharge. I am 26 and after having my son i have had brown discharges and light pains, i have been tested and nothing sinister just scarring after the birth.
But i will say this, discharge of any nature is perfectly normal however a smell to it could be an infection but dont panic it may just be a yeast infection which is very common and easy to clear up there are products for things such as thrush (a rash that is red and itches externally) readily available in any chemist. Generally brown discharge is old blood or the lining of the womb shedding but if you are worried please go to your GP they are very discreet, no one need know and it takes 2 secs for them to give you the check over.
For those that are not sexually active or started a period it is your bodies way of preparing itself for what lie ahead remember we are mainly for reproduction and that takes a lot of prep work for us ladies so it is fine.
Everyone else dont panic that you are pregnant either brown discharge does not instantly mean that you are this could just be because you have recently had sex and the contractions of the vagina has moved some old blood but please ALWAYS use protection.
Finally NEVER overdose on the pill if you miss one then leave it and continue as normal but avoid having sex for a week just till you are back in sync this is VERY DODGEY. And dont rush in to thinking that the pill is the only answer to contraception as there are risks tied to it, i started on dianette when i was 15 and at 17 i developed a
breast tumour the docs didnt link it to the pill then one year later i got a blood clot on my lung that nearly finished me off it was only then they realised i was having a reaction so be careful, if it works for you great but if you are not getting on with it look into the mini pill which is safer or the implant or make him do the work and get condoms after all we have to put up with all the rest right.
I hope this helps i thought you could all do with some answers but my best advice is if in doubt see a doctor you may be making yourself worse by worrying about something that is not nessesary x