Brown things in pool and metal stains

I'm hoping you can help me because my pool service company ignores me and I'm going nuts trying to figure this out (I'm on my 3rd pool company as others have gone out of business or didn't show). I think I have two problems - I have light brown/yellowish stains under tile line and spreading throughout bottom of pool. I tried the Vitamin C tablet per your forum and it seemed to remove stains under the tile line. The pool was replastered (white) last year but I've never had metal problems before. Is this from failure to maintain the water chemistry right? But I have very dark brown debris in the deep end that I can't figure out what it is. I can post pictures if you tell me how. They are small, squishy, flower shaped balls. I thought they might be some sort of animal waste (have tons of frogs that go in the pool at night - that's another problem!) but now I see they're flower shaped, and I'm not sure. They sit and cause large stains. Do you know what it could be? I had a tree cut back from the pool and I've had the pool 13 years without seeing these before. They are also not on the patio around the pool - only the water. Thanks for any help you can give me!!