LOL,too old? You are never too old... Regular arousal and orgasms are very important to keep your vagina and vulva healthy and 'fit' after menopause. It may bedtime to say goodbye to rougher sex and go for mor gentle sex.
It is likely due to menopause. Your vaginal walls gets thinner and do not lubricate or stretch as well as before. This is due to your estrogen and testosterone hormone levels changing.
Get some personal lubricant and make sure you lube up a lot and stay wet throughout.
The pain on deep penetration is likely due to him hitting your cervix. Your muscles may be sagging a bit that is causing that now. Remember to do lots and lots of kegel exercises.
Use shallower penetration positions, or close your legs with his outside yours. He can also try a penis ring to stop him from going too deep.
Best of luck!