I don't know how to help you and your post was dropping down to the bottom. My responding will bring this to the top so others might see it.,

I'll give you my standard care kit. Mix up a gallon of water with Neem oil to instructions on bottle, 1 tablespoon of dawn dish soap, 1 tablespoon of wet-table sulfur. Spry the tree with this and keep the tree out of sunlight for one day and keep the tree out of temperatures above 84 degrees Fahrenheit. This will kill fungus, spidermites, aphids and many other things you cant see. If you can, lift the tree and root ball out of its container and check for soggy and bad roots. Also check for very dry soil. If the soil is Dry then saok the tree in its pot for a half hour to get all the air bubbles out and then let it drip dry. If the roots are bound, then trim the bounded and wrapping roots and put it in a pot that is 2 to 3 gallons bigger. Use 5-1-1 mix unless you live in dry and/or hot climate. After all this your tree should start improving over the nest month. This is what I used to get through a crunch with soggy heavy soil mix.

Dont plan on growing this way unless you can only watet once a week during you hot summer months as I had to. My trees go 2 months between watering in the winter and I must draw air through to keep the roots fresh and oxygenated.

Eric...Have you ever called your maniciple water supplier and find out what the pH of your water is..? I would assume that the nutrients are all locked up in your mix because your watering solution is not acidic enough and you are using a good fertilizer regularly?...
The mix looks real good so can I assume that the roots are ok and not overly dry or overly wet..
Where do you live? Is your tree being exposed to too much heat or cold?
If you have good roots, even temps and good food, then I would attend to the pH thing ASAP...
Sorry for the inquistive questions. more details is always best, especially your cultural habits)
Mike

Are you using softened water? If so, not good.

Water softeners use salt and salt poisons the plant. Get your water before it enters the water softener or from an outdoor faucet that bypasses the water softener.

Thanks for the replies. I live in Hayward, CA zone 9b.

The Meyer is in 5-1-1 mix and has been for about 1 year. Drains well. The PH from the tap is around 8. I often add vinegar when i fertilize and bring it down to around a PH of 6. Not too much heat or cold. Pretty moderate area. All my other potted plants are doing well. No watersoftener. It gets 10+ hours of sun a day. I more recently have been using Earth Juice fertilizer, but usually i use Foliage pro.

Eric