Talk to Gynecologist on Menstrual Cycle

Assalam o Alaikum Respected Dr, I am a nursing mother of 8 month old , post pregnancy I started my periods regularly after 40 days , last month in july my periods were 4 days late 14 july , but this time it was much painful for me well i took shower on 21 (7 days ) but still had spotting for 2 more days than for 4 days it was normal and again i started having spotting till today , its not much bleeding but at start it was much painful specially my backbone hurt a lot bcz of this , its dark brown to reddish blood which is kind of spotting , i need any medicine recommendation or any test for this