Could a prostate infection be causing pain in my little toe when I have an erection?

Possibly; see doctor. One who gets pain at a little toe, while having a prostate infection and an erection, has an intriguing symptom, since the toe is about 3 feet from the prostate. However, nerves that come out of the sacrum (the bottom of the lower back) travel to the prostate, travel to the little toes, and also cause erections. The person may be getting "referred pain" to the toe. A neurologist can figure it out.