My son 10yrs old

[alinic]

My son has loads of allergies , asthma and eczema, but is resonably healthy, never in, we stay in the country, eats everthing, all fruit and veg etc.
But i have notice that his bone on his thumb , just down from his nail, is swollen, and sore, have ran through the ususal questions with him did he fall etc, but what am wondering could it be childhood artharitis (spelling!!) ,
There is no break in the skin and no sign of infection, skin is swollen and red, but not warm to touch?
Any ideas, or info would be great .
Manythanks xxx