Brown periods

I got off of the Mirena in June after being on them back to back for about 8 years. I just turned 35. All 4 of my periods since then have been brown. No bright red blood. Ive heard that some brown blood is ok, as it’s just older blood that is taking longer to leave your body. But my “periods” have been replaced by brown blood. I also have not have EWCM. Getting very worried. Please advise.