Light Spotting for 4-5 days

Hello, my cycles are usually 38-42 days and are normal length and flow.  A few weeks ago at day 33 I started to lightly spot for about 5 days (a few spots on pantyliner/day and more brown than red).  I took a pregnancy test and it was negative.  After 2 weeks from when that started I just started lightly spotting again like that.  I don't have any pregnancy symptoms like tender breasts, nausea, etc.  I am a healthy 29 year old.  Do you know what's going on?  I normally never spot between cycles.

[jen_KE]

I spontaneously started to spot before af a few years ago and it hasn't stopped.  Found out fibroids popped up and caused it.  Once they were removed the spotting got much less.  You might want to check that out.  They can see most fibroids or polyps with an ultrasound...