Brown Spotting No Period

Dyanna
Hello ladies,
I've been having some sort of issue with my period hoping to seek some help. 
My last "real period" (regular flow) was on March 21st. My next period was due once again on April 21st according to my cycle log. 
My period last about 5 days ( standard heavy flow ) . 
very regular - no previous issues other than the obvious of being pregnant. [ 1 child ]
On the 7th of April I caught the flu [ extremely nauseous, vomitting , ext. ] 
*added in just because I read this may affect menstral cycle). Negative pregnancy test
• On the 17th of April , 4 days before my next period SHOULD start, I stained my shorts. What grabbed my attention was the color, dark brown as seen in old blood. 
• On the 21st ( DAY I SHOULD BEGIN MY PERIOD ) I woke up extremely nauseous and threw up. That same day I took a pregnancy test and was negative. 
• On the 26 I took a second pregnancy test and still appear negative.
Today makes 16 days of on and off spotting. No menstral flow. Blood color still consistent dark brown. 
Any advice , suggestion , idea , help ?
Please & Thank you.