Help! Bleach and/or CLR has marked bathtub!

Hi! I'm frantically cleaning my bathroom of an older house for inspection. I used demestos in the bath and scrubbed with one of those green scours then rinsed. Followed up with diluted CLR (no cleaning knowledge didn't realise shouldn't mix!) I started noticing blueish/grey marks. Not sure if was bleach or clr?! Have I eroded the surface/ scrubbed off the surface or is it just stains?? Help please don't want to pay for resurfacing!!!