After 4 days of missed period, i had a skin like discharge on my pad (about 1.5inc) on my 2nd day pf period. what could it be?

An early miscarr: Possible u had an unsuccessful early spontaneous ab, or just excessive tissue , a + blood test would confirm the 1st one, u get a quant b-hcg and a progesterone, if + b-hcg then u get another one 3 days later to see if it goes up or down, if a normal pg it should double, if an early missed it should be going down, so see your obgyn to find out.