Here's the timeline of what I've been experiencing.

Day 1
In the early hours of day 1 I woke up with a bloody nose. Cleared it up and went back to bed. Midday I have completely black bowl movements (like sharpie black, not dark from protein or something.) I figure I must have swallowed some blood. By evening I noticed a small red patch with a cluster of small clear blisters on the shaft of my penis.

Day 2
Blisters still the same and bowl movements still the same.

Day 3
Blisters must have popped because it turned into a lesion and starts to scab over. I used some liquid bandaid over the scab. Bowl movements still black.

Day 4
In the morning, I notice two small blisters adjacent to the original cluster. Liquid bandaid them too. My bowl movements are returning to regular color now.

Day 5 - 9
I start cleaning my penis with alcohol swabs, and use Abreva and Neosporin as well. Things are healing up and I haven't seen anything new.

I've been in a monogamous relationship for close to 10 years. My partner and I have each had another partner previously otherwise we don't fool around. Neither she nor I have ever experienced anything like this.

Any idea what this could be?