Hi there. It does appear that what you are describing is a 'pilonidal' sinus
problem. This affects the hair roots etc in the region that have got infected & may be tracking deper. You may require a small surgery to evacuate said contents & drain the region & need to visit a local surgeon. In addition a course of antibiotics/antiinflammatory agents like brufen
may help reduce the swelling. Cheers & Good luck!