Hi,
the ozgood slaytters is a common mis diagnosisn on the peripheral arthritis (I got that one at 25), be it IBD SpA or AS etc.....William is worse than me age and involvement but it's very similar in it's distribution.
Needs a good physical to check out the other joints and esp looking for enthesitis. (SpA specialist rheummy)
Will was riddled earlier in the year. If I had n;t had it and as bad we would n;t have known, in the end he was so sore and swollen and stiff you had be blind to miss. H
e's improved some!
Hopefully your son is just OZ/SL, which is an enthesitis thing but softness in youth as opposed to semi-permanaent inflammation. Fingers crossed!
David