Clots

So I had a miscarriage back in May and I’ve had about two periods since then, after I finished last month I started taking the combined pill, I stopped taking it about 5 days ago but my period is due tomorrow, on Wednesday I noticed some brown snotty like mucus when I wiped, now I’m bleeding but Ita mixed with brown blood, I just went to the loo and passed a biggish clot ( smaller than a golf ball ) but definitely bigger than what’s normal, can anybody help me on why that could have been?