Hi, It sounds like you have an infection in the area where you cut yourself. The diarrhea certainly could have made it impossible for you to keep the cut area clean and foster an infection. The whitish blister could be pus in the course of the infection. I would suggest you do sitz baths with betadine (contains iodine) diluted solution (unless you are allergic to it) and after the infection has cleared with chamomile tea or black tea. That helps to heal. I am also concerned about your fever. If this does not resolve within a day or two, you should immediately see your physician. Also if it doesn t get better with the means I suggested, see your physician about it. If there are more than one blisters, you could also have a herpes or shingles infection which requires additional treatment. Let me know how it turns out. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. Christine Sauer