Someone else posted about this yesterday. There are several different fungal infections that can be the cause. I put a link in that post with photos, etc. I'd spray these with a fungicide asap. I use Daconcil on mine. They usually have it at Lowes or Home Depot.

I sure wish someone would answer this because I have the exact same problem. Had it last year and it affected all my plants and I'm seeing it again this year already.

In cold Zone 6 in the NE, established/new camellias may sometimes temporarily loose leaves after very cold temperature drops, just like other shrubs do but they will leaf out later when temps warm up. But in Z7B, if there are no injuries, it would be a bit rare unless there were big dips. I have not had foliage issues due to temperatures as cold as 13F in January but, if a new, not-yet-established camellia did not have enough soil moisture before these wild temperature dips, it may have started leaf browning issues. Your big dips probably happened in Nov 22-23 ish; and Jan 21, 30-31-ish. The single digits in January of this year probably caused the problem for this shrub. Lack of sufficient soil moisture in the top 4" in a dry (warm or cold) winter may cause leaf drop. To prevent the loss of leaves and-or buds, I water deeply & mulch on the night before those very cold, wild temperature dips; or that you water on dry, warm winters where the soil has not frozen;.I maintain 2-4" of organic mulch. When I turned off the drip irrigation once during winter.... and forgot to turn it back on... I started to get browning of leaves during dry, warm, late winter months. Then, as blue bayou mention, there are leaf pests.... :o(... double sigh.... although they eat the leaves and not make a leaf suddenly turn brown without injuries unless a branch was eaten/damaged further below. Remember that this is a newly planted shrub so it needs to get water where the pot's potting soil is located. When watering, start near the base and water outwards around it and water only the soil, not the leaves. You can very carefully and lightly scratch some branches to see if you see "green". It should be time for leaf out this month. I suspect your are probably close to being done with frigid temps. Knock on wood!

any cold event in the last few weeks?.. big city location would help .. as well as the pictures ... ken