I know this may sound a little silly, but perhaps you should make a scheduled time for him to do something to ease his stress. I know hot bathes with champagne, or extra long sleep-in time on the weekends does a world of wonders for me. Granted, he's not going to be sipping on champagne in the tub, but perhaps you just need to find something that helps him. Make sure he gets his sleep, and maybe every day for one hour he does something enjoyable and relaxing for him no matter how much homework. Perhaps it's playing a video game, taking a swim at the community pool, or just watching his favorite TV show. On the weekends you could make it a habit for him to do something special like see a movie.
When he's studying, make sure he's not doing marathon studying. Studies show that we don't retain much information after 15 minutes. So perhaps make it a habit for him to study for 15 and take a 5 minute break, and then go back. Making a scheduled list with everything he needs to do for classes helps him visually see what he needs to do. Encourage him to take his assignments one at a time so he doesn't get overwhelmed, and once he finishes something to cross it off. I find it to be a relief to visually see the things I've done crossed off the list.
As for social issues, I can empathize. 13 is a rough age, and kids can be so judgmental. I was always a bit socially awkward at that age, and didn't have many friends because of it. I matured way too fast, and just couldn't relate to my age group. I know this sounds horrible, but I found relief in playing online video games. I especially liked city of heroes. Playing a super hero fighting crime was fun, but also I was able to talk to others in game giving me someone to socialize with. Although this may not make a completely healthy relationship, in limited amounts it provided some relief by giving me another human being to speak to and relate to that wasn't so judgmental.
I also find making sure I take a multivitamin and a vitamin B complex every morning with breakfast helps me start off the day right. I feel better overall, and the B complex gives me a natural energy boost putting me in a better mood.
When I was having issues with milk, I would limit it to once a week. Usually I would make a point to treat myself to a bowl of Coldstone cake batter ice cream. That way I didn't seem to have digestion issues, and I was treating myself.
I really would just try to change things in small ways. Helping him see things one step at a time, rather than the whole picture will help to keep him from being overwhelmed and stressed. Getting at least 8 hours of sleep is absolutely crucial, i prefer 9 hours myself. I'm not sure if this helps at all, but it does sound as though stress could be a crucial factor in this. You'll just have to work together to find what's perfect for him to melt his stress away.
Kitkat, thanks so much for the reply!
You are right, stress does play a role. I, too, have similar stomach issues with milk and with stress, so I know just what you mean.
I know he's only 13, but yes, his life does have significant stress -- he has an anxiety disorder and OCD, which creates a lot of internal stress, plus he has some social issues at school which I know adds a lot to his stress-load. Add in all the days he's missed and faltering grades -- well, let's just say it's been a rough year all the way around.
I just can't seem to find the right combination to give him relief....
I know this may sound odd, but I tend to be lactose intolerant and beef intolerant when under high amounts of stress. When I was in college I was eating poorly, had gained some weight, had long hours, and was under a lot of stress. Dairy and beef would cause constant digestion issues, but would sometimes not cause any problems. Lactaid never did anything for me. Sometimes it was the amount I ate that determined if I would have an issue, but after I graduated things changed. After changing back to healthier eating habits, and relieving a lot of stress things are back to normal. Granted, if I ate a cheesy dish with a glass of milk, and finished it with a bowl of ice cream I would still hurt now, but I'm a lot better off than before. I know my father has the same issue, if he's under a lot of stress he's lactose intolerant, and he's been that way since his early teens.
I realize your son may be 13, but he could be under a lot of stress from school. Perhaps it's something else that triggers his issues. It could be the amount that determines if he has problems. Have you tried a diet change? I know I'm a lot better off when I eat vegetables. I'm not sure if this helped you out, but I hope it at least gave you some food for thought!