Implantation Bleeding Or Abnormal Period?

Hi everyone-- this is my first forum post!

A little back story: I still nurse my now fifteen month son, and was not getting my monthly periods for a while or ovulating. In late August, the obgyn prescribed prosgesterone pills for ten days and then three days afterwards, my period came Sept. 1st until the 5th. I then found out through a blood test that I had ovulated this month, but I do not know when. I have had sex with my partner the week that I might have ovulated. Well, yesterday, I felt I was leaking and come to wipe, I found watery, brown discharge. It is now the second day and it has only been dark brown, not enough to fill a tampon or pad. At night, there was a bit of red but this morning, my pad was once again not full and dark brown. I've had implantation bleeding with my first pregnancy so now, I don't know if that is what Im experiencing. The blood work I did that indicated I had ovulated said I'd get my period within two weeks. My expected period is Oct. 1st. Could this be an actual wacky period from the after effects of last month's progesterine pills, is my monthly period a shortened cycle (not even the average 28 days) or could I be pregnant? I tested the past two days and they were negative. I don't know if it is too soon. My doctor told me to call when my period arrives and ignored the possibility of implantation bleeding even though they said I would receive my period in two weeks or would be pregnant. Has this happened to anyone else? What were your experiences?

Please Help !
Thanks !

I didn't find the right solution from the internet.