Am i bleeding internally?

for two days now I have had a noticeable amount of BLACK tarry stool while using the toilet.. the day before yesterday it was very little, and just an hour ago the amount has increased. I suddenly had the urge to go, and it burned pretty badly, and now my stomach feels very funny as if something is boiling in me, it's not unpleasant just unwanted. on my birthday 23rd of june i had my blood drawn when i went to for a check up, when i was being examined i noticed the doctor said something like " that's pretty odd" when he was touching my lower abdominal area, i neglected to ask him what he meant, but now that i think about it, I'm really concerned... i heard u can see if u have any gastric issues if u get your blood drawn or something like that, so I'm waiting for the results, any help and or advice on what could be the issue? please and thank you.