The solution to pollution is dilution. Run the water for a very long time at an outside faucet or at the well tank. Like for HOURS.
You DID use Never-seize on the bolts of the cap after you put it back together so the next person to come along doesn't have the same problem as you?
The next person could be you again or someone like me who will have no end of names to call the person who installed a nut and bolt fastener without using any form of thread lubricant.
How do you get insects (like ants) out of a well when they go up the electrical conduit and make a nest on top of the wires and pull rope. And when they die, the colony pushes them out of the nest and the bodies come out of the tap in the house? (Same answer to your problem)
Pull the pump, have the driller or someone stick a piece of pipe connected to a large air compressor hose down to the bottom of the well and re-develop it.
That's what I did .