thanks for writing.
Any protrusions suggest sinus
A sinus is a track connecting outer and inner parts of body.Outer part is on skin,and inner opening can be deep extending in to muscle,bones etc.
Common cause of sinus are tuberculosis
,and chronic osteomyleits.
A sinus has to be drained surgically and for this you need to consult a surgeon.After drainage
you need to take antibiotic course for several months.
I hope this can solve your problem.Take care.