Having dusty brown discharge with white.

I'm in harmonal pills I'm confused whether i had miscarriage before 5 months  i had all symptoms After that this problems were coming. On April second half i may be pregnant. Late at june my periods started with spotting and it lasts heavy from june. I took harmone pills but on 16th day of tablet my periods came.. On july i didn't have periods. And on August 22nd i have started with spottings that's like dust in colour. It stops automatically.. And same date i have same like spottings on next  month And from October 28 spottings came but it lasts long. And i took harmone pills for this 5days.. It completely stops after 3 pills.. But from 4th day same dusty spotting came. It seems not like blood. More like a dust.. Having sides pain back pain vaginal pain. Pls help me..