Welcome here on hcm.
Actually high dietery calcium prevents kidney
stone formation so your doctor is wrong here.
Secondaly a need and risk has to be balanced for supplimenting calcium.
Yes Vit C increases risk of kidney stone formation but again its need and risk has to be balanced.
NAny one sided decision will cause other proble.
Cance risk increase with the ageing and for that reason people will not leave living on planet.