Brown spotting and small flakes

Torie
Yesterday I had some brown spotting, I went to the doctor and she said that it was perfectly normal at this stage (4w5d).
She did a blood test to confirm postive pregnancy, and one for all the levels. She set up an ultrasound for the 29th and to have bloodwork done again to make sure HCG is increasing accordingly.
Today I went to the bathroom and there was nothing initially.
The second time I went to the bathroom after I went pee I noticed some small brown flakes in the toilet and it was brown when I wiped.
About an hour later I was standing and felt something warm so I went to the washroom and wiped and there was a darker brown on the toilet paper almost black...
I've been a few times since then and there is definitely still brown when I wipe and there are still brown flakes in the toilet.
The doctor said yesterday unless it's red or pink and the cramps are extemely painful it's nothing to worry about.. But it's hard. It's my first pregnancy and I just was wondering if anyone else experienced this?
Tomorrow I'll be 5 weeks.