Thank you for your query on Healthcare Magic.
The pain of the scar may be due to inflammation caused by the rubbing because of clothes.
Some times hypertrophy of the scar will lead to erythema
For pain you can take ibuprofen
in prescribed dose.
And if there is secondary infection it has to be treated by application of an antibacterial cream.
Consult the doctor for clinical examination.
Hope I have answered your query.