I have an extremely irregular period but based on my phone's app, my period is late for about 3 weeks and I'm aware that high level of stress and irregular sleeping hours could be contributing factors as I have experienced that for about 2 weeks in a row.

However, I have been getting brown and clumpy discharge/spotting for the past week. There's quite a fair bit of brown clumpy discharge shown when wiped and I have to wear a pantyliner as a little bit may get onto my underwear. The discharge also has a strong fishy smell.

I'm sure that I'm not pregnant because I've already taken 2 pregnancy tests with a week's gap for each test. It would be greatly appreciated if someone could tell me what's going on.