Definitely it could be fistula in ano, for confirmation you can do either sonofistulogram or MRI fistulogram.
If it is fistula then don't wait for oral medicine or natural way of healing, there is no chance. Better get kshara sutra treatment from nearby Ayurvedic surgeon that will give you good results
If you go on delaying it become more complex and worst
Next Steps
Examination by speciality consultant
Health Tips
Kshara sutra treatment