Not familiar with the colorQ7 testing accuracy for CYA, maybe get a 2nd opinion from pool store testing your water or friend with a Taylor or TF100 test kit.
If it is truly at 100+, I would drain and refill to get to ~45-50ppm. Use the pool calculator based on your best test results for CYA level to get the % of drain and refill needed to get back to 50ppm.
As far as it being safe to swim now at your low FC levels, first I would add enough liquid chlorine bleach to get up to the recommended levels. Check your CC levels. CC levels above 0.5 indicate the chlorine is fighting something in the pool. Maybe wait one day and retest. I'm sure it would be ok to swim if water looks clear and tests do not indicate problems. We swim in ponds and lakes all the time with no problems but use your own comfort level to decide.
