The stinging sensation may be due to vaginal dryness
or lack of adequate lubrication during intercourse. At your age even if the vagina looks healthy on pelvic examination, the sex might be painful due to lack of lubrication. It is a common life event so do not worry.
Use copious amounts of K Y gelly inside the vagina, apply with an applicator or ask your partner to apply inside for you as well as over the tip of his penis before insertion will most likely solve your problem. Both you and your partner should be supportive of each other and you will definately be able to enjoy your sex life.
In addition for your hot flashes you can try simple remedies,
Reduce intake of caffeine. Eat more proteins
and mineral rich foods. I hope you are on regular calcium supplements
like Citro Macalvit. For your hot flashes you can try taking Tab Menosan by Himalays, two tablets twice a day for at least six months. Do take up some exercise activity like walking or swimming.
Be good and healthy.