There are a few things to consider here, the first being that fish and shrimp at your turtle's age are more like occasional treats than usual diet items (which you were wise to cut back on). Excess protein leads to unnecessarily fast shell growth, and in the worst cases organ damage. Just wanted to point that out, before anything bad happened.
Secondly, are you sure it's a male? Gravid (pregnant) females tend to go off feed, while adopting frantic activity patterns as they are searching for a nice nesting site.
Third, have you seen him basking or pooping lately? Those are both good indicators of digestive activity; a lack of either of them may point to your turtle not digesting properly enough to warrant further eating.
Finally (and this is the simplest possibility), have you tried just walking away after putting in some pellets and/or vegetable matter? Your turtle may just be getting excited for feeding time, and as long as you're standing there it may not notice that there's food already in the tank. I apologize if this part sounded a bit like an insult-your-intelligence question, I just wanted to double-check

. Sometimes, the simplest explanation is the best one!
Don't worry too badly about the lack of eating yet. RES can go a long time without eating. The red "ears" (I'm assuming that those are the "spots" you're referring to) fading are probably a result of aging.
Also, a description of your setup (tank size, water/basking temperatures, etc.) would really help us!