Coliform re-occurence after shocking

We recently went through an "odd smell in the water" situation that came back as both TC and E Coli in the water.
We shocked the well and re-tested a week after the chlorine was gone. E Coli was gone - but Coliform still present.
Shocked the well again and installed a Sterilight UV filter (SQ8-PA with a UPS) post sediment filter and softener so we wouldn't have to worry about the water in the house.
Re-tested the water again after a week and raw water (sample from storage tank) was still negative for E Coli but still positive for Coliform. Treated water was fine.
I had previously suspected earwigs - as the old well cap was not very good and not tightly sealed and upon opening it - there were dozens of earwigs running around inside the well pipe. The new sealed cap has kept the earwigs out - but I still have the bacteria issue.
What should I be doing to investigate the source of the bacteria? I would rather fix the problem as this well was bacteria free for years before this outbreak and my father who visits frequently has a compromised immune system so althought the UV works fine - I would rather consider it a safety net rather than the only thing keeping the water safe.
Also - any ideas on why the E Coli was there, then gone while the Coliform stayed? The smell has been consistently gone since the first shocking.
thanks!
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Hoping for some insight on next troubleshooting steps. Hire someone to inspect the well with a camera? Inspect septic? Thanks for any advice
sting7777 wrote:

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