Hi thanks for posting your query on health care magic
The stomach ache which you, have from last 3 days following drinking and eating spicy tacos, along with diarrhea
is due to gastritis
(inflammation of stomach)
Drinking and eating spicy food, can produce gastritis.
Diarrhea could be due to infective process, which may have occurred along with the food.
However you have not mentioned the colour of the blood.
Was it bright red or dark tarry?
If it was dark tarry, then it could be due to bleed from stomach, as part of gastritis,
However if the blood was fresh and bright red, it could be due to bleeding in your anorectal
area,may be due to straining on stool or due to some local pathology in the anorectal area
Hope I answered your question.