Andrea, I had my bypass 7 days ago today and I have had the same thing for days, sometimes it is enough to use a tampon and then a couple of hours later it is a brown discharge. I wouldnt say I have had cramps but there is a definate feeling of it could be a period coming.
Saying that though I had the same thing the night before the op and some period pains and I havent had a period for about seven months before that. Bearing in mind I had just done the two week pre op diet and lost a nice amount so I am taking it that my body is noticing the difference and having some effect on my hormones but because our bodies are technically in a state of flux it doesnt know quite what to do yet.
Im pretty sure we'll both get it sorted soon, our poor bodies just need to work out what is what.
Good luck hon xx
Steph xx