Thank you for the added information.
It is likely that you have developed an infection known as Bacterial Vaginosis
(BV). This is not an STD but occurs due to a overgrowth of bacteria like gardnerella. Gardnerella is a normal bacteria of the vagina but under certain conditions when the ph of the vagina changes, it can grow too much and cause inflammation of the vaginal walls
. This will cause pain.
A common cause of Gardnerella overgrowth is use of antibiotics. Antibiotics can kill off healthy bacilli of the vagina like lactobacilli which keeps the ph normal.
Treatment s with antibiotics like metronidazole or tinidazole which prevents overgrowth.
A greenish vaginal discharge is seen in a an STD called trchomoniasis. This condition can not only cause pain but also itching of the vagina. Although you have been married for a long time, if metronidazole dose not help decrease the pain, you will need to get this checked out.
To decrease the burning, you can use a vaginal moisturiser like Replens, available without a prescription - it will decrease the dryness and inflammation to some extent. You can also take an oral anti-inflammatory like Ibuprofen.
I hope this helps.
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