A burning feeling inside the vagina with no discharge, itching, odour or urinary symptoms is less likely to be an infection and more often points to dryness or irritation, sometimes from soap, sweat or hormonal changes. Since it has lasted over a month, it is worth having it looked at properly rather than just increasing water intake.
Next Steps
A vaginal examination with your gynaecologist can check for dryness, mild irritation or an early infection that isn't obvious yet, and a swab can be done if needed.
Health Tips
See a doctor sooner if discharge, odour, itching or pain during intercourse develops.