Phalaenopsis trouble on the leaf

[gul]

Hello,
When I noticed the signs of a probable sunburn or fertilizer burn on the tip of my orchid leaf I took it out of its pot, cut and cleaned some rotten roots, wiped the leaves clean and spread some olive oil on top of the leaves. I decided to monitor the situation for a time so I didn't repot the orchid immediately. Instead I put the remaining orchid roots in water in open air during daytime and take them out of the water during nights to promote new root growth because there are only a few roots left healthy. For a few days the trouble on the leaf seemed stabilised, it didn't seem to proceed. I even was surprised and delighted to see that a new leaf formation had begun. However, I just noticed that there is probably a more serious problem on the leaf than I dared to hope for. So what could be wrong with my orchid? Should I cut the troubled leaf to save my orchid?