The smell + the difference between your OTO results (>20 ppm) and your DPD results (~16 ppm) suggest extremely high combined chlorine levels. Do this:

1. Check your pH using the test in the K2005. But, first do a 50:50 dilution with DISTILLED water. The pH result does not have to be adjusted, but read it quickly. The phenol red in the K2005 is compensated to ~10 ppm TC, or 20 with the dilution, but your TC may be higher than that.

2. If your pH is below 7.8, add borax, a box at a time, till you reach ~8.0.

3. Then, begin adding bleach -- but first tell me how many gallons you have OR what your the pool's dimensions are.