Like a period but not a period?

So last month when I was suppose to get my period I instead got brown discharge that basically just looked like old blood and uterine lining. It was so light I didn't need a pad or tampon so I thought it was just my period starting. Well it stopped after four days. And I didn't get my period at all. Took two tests about a week and a half later, both were negative. So I'm like k whatever I'll skip a month. Now I'm about a week out from my next period and boom more brown stuff. It's like I'm on the last day of my period but I'm not. Anyone ever have this issue? Any advice?