Tolumnia Jairak Rainbow: Help!

[abigaillevans]

Months ago I inherited a sick tolumnia "Jairak Rainbow" from someone who didn't know what to do with it. It was sick and dying when I got it. I've kept it alive for five months: it hasn't gotten better, but it hasn't gotten worse.

Here's the rundown:
-Planted in charcoal pieces in a 3" terra cotta pot
-Sits on a patio facing east under an eave -- it gets a couple hours of strong light a day, and is in shade the rest of the day
-Is allowed to dry before watering -- it's watered every other day or so
-The pot sits on top of pebbles in a saucer
-Is fertilized "weakly, weekly" with 11-35-15 Better Gro "Orchid Bloom Booster" (this is what the grower sold the woman who gave me the orchid)

Pictures are attached.

Any ideas? I throw myself on the mercies of the people on this board!