CRP is significantly related to PAD.
Although CRP levels can be increased due to any inflammatory process or infection going on in body, still, its increase is positively associated with PAD and atherosclerosis as an inflammatory process leading to PAD.
Increased CRP levels are more precise predictors of PAD severity when there aren't other conditions (hypertension, diabetes), contributing to PAD.
CRP less than 10mg/L is considered normal, so the rise isn't so dramatic.
Symptoms of PAD can be helpful for determining the severity of condition.
For example, if he had started to experience pain in his foot or toe while resting, sitting, and not just after short walk, so, it is very possible that his PAD has progressed to worse.
Doppler ultrasound of arteries will give you the right answer about possible worsened narrowing of the peripheral arteries.
Consult a thoracic and vascular surgeon!
Best wishes!
Marija
