Some fish just have a problem with QT. I have a kole tang that hid the entire 76 days he was in quarantine. He never came out to eat when I was near, though I did see him come out from across the room. I had to check on him with a flashlight to be sure he was still alive. He was very stressed the whole time. He completed Qt and went back into the display and is still happy and healthy. He's much more bold in the DT.
As long as he's eating, he has a chance.
If you started metroplex, then finish with that before doing any other meds. If you need to do prazi now, then switch to general cure since it has both metroplex and prazi and will take care of both at the same time.
Does the solorensis have any abnormal markings on him? White dots, dusty or dirty looking, red or white patches or markings?