Hi Doctor, I Have Recently Been To The Doctors Where

hi doctor, i have recently been to the doctors where he ashored me i was having pain in my lower back and lower abdomain from constipation, i have been put on a diet of high fibre to help my insides, 2 days after diet starting i have finally been able to pass a full poo, but have realised i have pain in my what should i call it ass hole is tender to wipe, is this due to passing so much or should i be worried more??