Green Pool after shocking. Started with treating brown stains on bottom of pool...

Inground pool, DE Filter - 25,000 gallons, vinyl liner.
Noticed staining on bottom of deep end about 4 weeks ago. Shocked and shocked, swept and swept with the broom, did not come up (brown-ish stains). I was told it could be mustard algae and sold a chemical to treat it. didnt work... went to another place for a second opinion - tested my water, all levels were good. They sold me Super Erace assuming the stains were metal related. I put that in last Friday as instructed and the pool was very clear but the brown stains remained. They concluded that it was mold under the pool liner and I needed to completely replace the liner.
I just shocked the pool because some green was forming in the corners and walls (3 pounds of shock) and the pool almost IMMEDIATELY turned lime green and slightly cloudy. After some research, it looks like this could be metal related? I have never ever had this problem before. If you could help me with what to do next, that would be so helpful. The stores are not helpful. This "green" after shock leads me to believe that the stains are metal stains maybe?

Closing this thread since you have another one going about the same problem.