Barry,
The base of the 5th metatarsal normally protrudes outwards (everyone take off a shoe and look at the outside of your foot. The protrusion midway from front to back is the 5th met "styloid process"). The peroneus brevis tendon attaches to this protrusion, and thus the bump can't simply be cut off.
See a foot specialist for an x-ray if you haven't had one for a while.
Calcaneus fx can heal with excess bone formation, which may be the cause. Intra arcticulal calc fx generally have a "lateral wall blow out", meaning the entire outer edge of the calcanues fracture into many pieces (like an eggshell) and as they heal, these can protrude or even put pressure on the peroneus brevis tendon, that attaches to the 5th met styloid process.
Or, the bone may have healed crooked, making that foot lean outwards or inwards.
See a specialist.