I would check the bulb 1st, then check wire connection, then fuse. If wiring prob, maybe can add relay to solve it.
Change fog lamp only also can, can use back d ori wire connection, unless change to really much higher watt bulb, then need to change wire & add relay as well.
Take note one thing, if its not ori one or just something look-a-like, have to beware whether it can shoot its light to front way or it shoot side way, bcos the base may be not so compatible to ur bumber if its not ori one.
This happens alot to wira fog lamp (after mkt look-a-like type), always shoot side way only. (Wira ori fog lamp 3 screw type for 1.6 cost rm200+, after mkt look-a-like 2 screw only rm30+)
Wira ori one (3 screw type) really bright & shoot front way, its like a mini projector lamp if cover taken out