Ongoing Problem

I have a problem where if I eat a certain food, not sure what it is, but it makes me produce rather large and dry stools. Large enough that it takes quite and effort to push out and when I wipe there is blood. Just yesterday when I went it was not too large but there was still blood as if there was a cut that wasn't healed. Other days I wake up and have diarhea (excuse the mis-spelling of that). I just don't understand what I am eating or not eating to make my body be like this. I took fiber pills awhile back but that didn't help. Mineral oil usually helps. But I would like to know what I should eat and should stop eating. I know that excedrin was part of the problem. I stopped taking it for about a month and I was pretty much okay. I took 1 excedrin pill recently to get rid of a bad headache as a last resort. I guess maybe that needs to run out of my system completely. Please, any suggestions will be greatly appreciated.