hi, thanks for posting
You seem to have ingrown hair , also called pseudofolliculitis
Ingrown hairs tend to be more common in areas with coarse hairs. Hair that is cut short and close to the skin creates a sharp tip that can more easily pierce the skin to cause an ingrown hair.
by shaving, waxing can be the cause and friction from tight clothing may worsen the situation.
The following may help you:
avoid shaving till the lesions heal
apply hydrocortisone cream
to reduce irritation twice a day
once they heal :
shave with proper lubrication
avoid shaving too close to the skin
consider permanent hair reduction with laser
this doesnot seem to be related to champix
Hope this answers your query