Brown Spotting/discharge

Ally • I'm Mom to 3 beautiful boys. I'm excited to add a 4th little BOY to our family!
Hi all - I just noticed some brown discharge in my underwear and a very small amount when I wipe. I do have some pelvic discomfort also but not really cramping. I did workout for 20 mins today on the elliptical machine... I'm nervous. Anyone else experience this before?  This is my 4th preg and I've never experienced this.