Hello! Newbie needing help with child

Hello everyone! I am new to this forum and am seeking help for my child, spouse and myself.  I have two children, a daughter (18) who has always been thin(5' 6" and 112 lbs.), just like I was until after having my children son (just turned 13) who was tiny as well until around age 5 when he just started getting heavier fairly quickly.  He is now around 5' 6" and 238 lbs.  My husband was always thin until after high school and has struggled with his weight as long as I've know him (15 years) and would be considered obese.

I really try to keep healthy food around, we rarely have things like chips or sweets sitting in the cabinets or refrigerator.  I have never been really great at denying my son junk food when he asks although I try to limit size and quantity.  The problem I have is that he is constantly eating and most of it he sneaks into his room.  It happens all the time that I go to make something for his/my lunch or dinner and find that something I needed has been eaten up.  The thing is that it is never a small amount, but the entire bag of grapes or carrots, the whole block of cheese or all the lunch meat.

I try to keep him busy, especially this summer, he has been a counselor in training at the YMCA and been in 2 theater productions requiring several hours of practice whi*****ludes dancing, but whenever he's home he usually just stays in his room watching videos on his phone and eating.  He has put on over 8 pounds this summer. 

 I tried going back to work this spring after being a stay-at-home-mom for the better part of 13 years, but within about 6 weeks he gained 30 pounds and all his school grades dropped significantly so I stopped working to come back home and have tried to prepare healthy meals again, I did a terrible job when working.  We are trying to eat the mostly Paleo style diet that we were eating a year ago when we each lost around 20 lbs.   I worry about both of my boys because diabetes runs in my husband's family and they almost all struggle with obesity.  I have also had gut issues, diverticulitis 4 times in just over a year and hospitalized 3 of those times.

Sorry for the long post, but I hope some of you have some words of wisdom for me.

Thank you!

You should have the doctor order labs on them a full set, they may be lacking something g or have thrived issues......   See if you an get into see a dietician.... So they can give you guys better ideas on what he can eat!  

Nancy, thank you for your reply.  We have had a few tests done on him and so far he hasn't tested positive for anything.  We have also met with a nutritionist who gave me no information that I didn't already know.  He is due for his annual physical again soon and I will talk to the doctor about possible failure to thrive and see if we should test again for anything.  Is there any real difference between a dietician and a nutritionist?