My Son Has Had On And Off Stomach Aches For

My son has had on and off stomach aches for years. He is 12. Two years ago I noticed a hernia, which I was told was an epigastric hernia, and he had it removed. The doctor said that type of hernia typically happens when you are born with a small hole in your stomach. He had no issues after the surgery, minus the few random days he would say his stomach hurt, up until recently. For the last few weeks, almost daily, shortly after he wakes up he is really nauseous. He is feeling car sick more often, he says his stomach hurts, his throat hurts when he swallows, and from the sounds of it, it sounds like he has acid reflux, too. When he feels nauseous he says his legs feel weak. Last night he pointed to about his belly button area when he said his stomach hurt and I asked where. He's always moved so slow when he goes anywhere, unless of course, there is a bag of candy to get to, and then he can move pretty fast. I feel like he moves slow on purpose half the time, though. He is a skinny kid, always has been. His little brother has passed him up in weight by 20 pounds. He is a picky eater, and I feel like he has had dark circles under his eyes since he was a toddler, but no one seems to notice I guess. I think it was chalked up to slight allergies. He does sneeze more often than others, usually several times in the morning, but I doubt any of that is relevant. He has also had one eye that is red on the outside, for a long time, however the doctors say it is no big deal. Im throwing as much out there as possible to see if anyone has any ideas. I took him to the doctor yesterday and they did a urine test and blood work. His urine showed a few keytones, a few proteins, and a few blood cells so they sent it off for more testing. He had swollen lymph nodes in his neck so they also tested for Mono. He did not have a fever, his vitals were all normal. Everything came back normal with the urine and blood. I'm going nuts. Any thoughts? Thanks!