Yellowing spotted leaves on Epi Wedding Valley

[Fran20]

My Epi Wedding Valley started developing spotted yellow discoloration on leaves of new growth. Some have fallen off. It was rootbound and had been growing in direct sun of a southwestern screened open window and circulating air from nearby fan prior to this. Avg. indoor summer temp these days is 84 deg. with 55% avg. humidity. I repotted in scoria and inspected roots and trimmed some dead ones and dusted with cinnamon. Majority of roots seemed viable and no pests observed. Wasn't sure if this is bacterial so I sprayed 3% peroxide on leaves only. To date I have had only limited success with nursing ailing orchids back to health, so your diagnosis and advice for further treatment would be most appreciated.

[estación seca]

The change to scoria meant the root ball would dry out faster. You're not watering enough. The plant looks very thirsty. These should have full sets of leaves on all the newer growths. In scoria you could water this ten times a day and not rot the roots.