Yes, it won't take care of the problem. It may add to it. You may have a lot of bacteria living in this well. Has it been sitting for quite a while?
Has it ever been disinfected?
You could try chlorinating it with a few gallons of chlorine chased by a 5 gallon bucket of water to rinse the chlorine off the pipes and wires. Let sit for several hours then pump clear.
If the chlorine doesn't work, you may have hydrogen sulfide which smells that way, but it always smells, not just part time.