Yellow leaves on Camelia

[Sprocket*]

Can anybody tell me why my camelia has suddenly started getting yellow leaves on the middle of the plant. I have had it a couple of years in a pot after getting it from Wilkinsons for £1.99. This is the second year it has flowered, this year over 100 buds (not bad on a bush 2 foot by 1 foot). Umm think I may have just answered my question, could it be exhausted?
It gets regular feed, camelia food and watered down worm liquid from my wormery).
Don't want to lose it as it is beautiful, dark pink with white flecks!

[srodders]

they usually say it's a lack of iron - you can add sequestered iron to a feed, but you say you already feed it (I assume a food for ericaceous plants). I have one in a pot as well and no matter what I do it gets yellow leaves - my opinion is camellias don't like being in a pot - the ones I have planted out I hardly ever feed and are fine. I plan on planting it out later and I'm sure that will cure it's problem

[Alice]

They like acid soil Sprocket so you could try top dressing it with peat and feeding it with sequestered iron. If that fails I would plant it with plenty of peat in the planting hole. Good luck.

[Two_Sheds]

I have inherited an established Camellia (pink - I hate pink) at this new house.
This year it has started to turn yellow, as has the other unidentified (poss. Viburnum) shrub opposite it).