Burning vagina?

For the past couple months my vagina on the inside feels like it's burning.. I had Chlamydia a month ago so I thought that is what was causing it but I got re-tested and it is negative.. but I still have this constant feeling up inside my vagina is burning.. no UTI either... Has anyone else had this before? What could it be? I also feel like I might be constipated.. I have a bowel movement almost everyday but it's usually hard to go or I feel like I still have to go but can't.. could that be what is causing it?

Edit- I only got tested for Chlamydia but my partner got a test for everything twice.