Take a deep breath! Some things to consider...it's normal for toddlers' appetites to decrease big time after their 1st birthday. So expect him to eat less, and as long as he isn't waking at night from hunger or losing weight, then he's just doing what toddlers do. It's also totally normal for them to eat next to nothing for a few days, only to eat you out of house and home for a few days. Toddlers have an uncanny ability to regulate their appetites according to what their bodies need, so you can't look at each individual day. I've read in many articles that you should look at toddler nutrition over the course of several days, even a week, to get an accurate snapshot of their diets. And it's also really normal for them to eat lots early in the day and taper off as the day goes on. You might try adding in a mid-morning snack around 10-ish, and if he skips dinner you could always try and offer a small snack right before bed. And I wonder what would happen if you offered food first, then milk? Or milk in a sippy with the meal? It sounds like he just wants milk, so switching it up might get him used to relying on food to fill him up.
It sounds like mealtime is becoming a bit of a battleground. He can probably see your frustration, and he's likely figured out that he can get attention by refusing to eat or screaming. If you aren't already, try letting him choose between 2 things at mealtime. If he isn't verbal yet, you can hold them up and he can point. If he doesn't make a choice, you choose for him. If he screams, mealtime is over. I wouldn't recommend scrambling to get him something else to eat. Comfort him, calm him down, and try offering the meal again. Try and be matter of fact about it and not make it into a big deal.
I agree with mum101 about getting something to go under his chair. My kid's 2.5 and still goes through phases when he prefers I feed him with a spoon or fork, even though he can do it himself quite well. I imagine he'll get over it eventually, but I have no desire to fight with him about it. And if he wants to eat with his fingers, fine. It's all part of the learning process. Hope that helps!