Mushroom coral dying??

[elgrcr12]

Got this mushroom coral in almost 3 weeks ago. I’m new to reefing but I have taken things slow and all of my other corals seem to be doing great. This coral in particular is stressing me. It was a greenish color when I got it. That may just have been from lack of light through shipping, but now it has turned a rusty orange color and has shrunk (I would say almost 2cm now). I’ve never had a mushroom before but I had heard they were one of the easiest for beginners. Please help. Alk, Calcium, Nitrates, Ammonia, and GH are all great except for pH which has been staying around 7.9. I am dosing twice a week to try to raise it. Is it dying or just adjusting?

 

[nezw0001]

I think it looks OK. Some level of color change is pretty normal with a change in type of lights.