Im 37 and have been trying to conceive for 2 years now with no luck. I was diagnosed last month with PCOS and started on glucophage. I know I ovulated this month - I am 5 days aways from AF. I have had extremely sore bbs which is very abnormal for me. Today I had a sudden about of nausea that had me running to the bathroom but I never vomitted. It was followedby a strange headache but everything subsided within 30 minutes. Then I was in the grocery and all of a sudden I thought I had wet my pants. TMI I know... it felt so thin that I didn't think it could be af. When I went to the bathroom it was very thin but also had a small amount of brown discharge. Solid brown not dark red or any pink, solid brown. Nothing appeared on the tp and I haven't had anything since and that was 2 hours ago. My question is does glucophage change the appearance of your periods or could this be implantation bleeding. I have two other children and never experienced implantation bleeding.

It could be implantation bleeding, but the only way to know for certain is from your doctor. Brown discharge could be other problems, or it could be just old blood.
Definitely a problem for a doc.

Can you tell me what you know about implantation bleeding? I have read so many DIFFERENT things on the internet that now I just really don't understand it at all.

All I know is that it happens at about the time the fertelized egg implants to the uterine lining. I didn't experience it during my pregnancy, so I can't give experienced advice.
A little TMI on my part, I have a cervix that leaks frequently, causing me discharge, but that isn't pregnancy related, though I didn't find out about it until after I had my son.
An exam should be able to at least come close to pinpointing the problem.
Sorry I can't help more.

Implantation bleeding is quite a rare occurrence actually. If and when it happens it is rarely even noticed. Actually, it has not been medically proven for many reasons. Those reasons are in the sticky at the top of the thread.

It is possible that you are just starting your period early this month.