It's not a houseplant, that's probably why, it'll hate being indoors year round - unless you've got some tropical variety I've never heard of.
If being kept as a houseplant (if you must) then it should be stood outside all summer, then kept in a room which is light, bright, cool and airy, with good air flow, and a temperature which does not go over 60degF, even better at 50-55degF. Needs frequent misting, repot in spring as necessary.

Camelia,s are outdoor plants, not house plants, it needs to be put outside, preferably planted in the ground, in acid soil, but as it,s been indoors I would gradually acclimatize it to outdoor conditions, if you have to keep it in a pot, use ericaceous compost, and don,t allow to dry out.

They are grown as house plants but the conditions they require are near impossible to replicate in this country. Cool position with indirect sun, moist soil and high humidity..almost no chance for it to thrive.

We tried growing our camellia in our front porch in a pot when we first got it... not a happy tree. Planted in the ground away from direct sun in the early part of the morning it grew and flowered extremely well until the early bad weather in November last year killed it as the sap was still up in the tree. Obviously you can't put outside now as it will be a huge shock to the tree but get somewhere cool and out as early as possible next spring.