Hi Natelz1, I hope this post finds you well.
I agree with everything that the others have suggested, I thought I might be able to add a little more, How does he sleep? on his side or on his back?. What I would suggest is putting a pillow between his knees or under his knees to give them some support.
Also there is aromatherapy that could help your son, by making a massage oil blend to ease the aches and pains.
The recipe is as follows. Eucalyptus 2 drops
Lavender 10 drops
Rosemary 4 drops
Tea tree 4 drops
1 small brown bottle with lid
which you get this and all of your essential oils from the health food shop. PLEASE GET 100% ESSENTIAL OILS SUNSPIRIT Is the best brand I feel, as I am super sensitive to smells.
Blend it all into a carrier oil such as Vegetable oil, yes the one that you most probaly have in the cupboard, blend the oils in about 30mls of oil.
When I make blends like this i go by smell, you should smell the balance of all the esential oils, there should'nt be an overpowering smell of one particular essetial oil.
Rub on before bed or as needed. I have used this blend on my family as well as my clients and it helps them.
Of if essential oils are not your taste you can use " A little Bit of Relief" that is an arthritis rub, it too has essential oils in it. It is also a Analgesic.
Also you could look into his diet maiking sure he eats more alkaline foods as acid foods attack the weaker joints causing pain.
I have a blog on minti explaining alkaline and acid foods http://www.minti.com/members/likes2chat2/blog/374474/Vitamin-supplements-not-working-for-you/
There is a bit on vital greens at first but please read down to the list of alkaline and acid foods. This too will help your son. Feel free to copy and past and print it up. I pass this information onto my clients as well.
I hope this has helped a bit and you find a treatment that suits you.
Have a wonderful day