Need Help Deciding What To Do Next!

[DCHI194]

Thanks in advance for any help that people give me.

Here's the situation:

My gf bought me a Phal for Christmas. I had purchased one back in 2006 but unfortunately killed it. I had talked about replacing it for years and finally my gf got me one. So needless to say this thing can't die!

It had a good amount of blooms when she bought it in late December (10-12) and they were very healthy for almost two months. Every so often one would wither up but for the most part everything was good.

In February the plant slowly started dropping blooms. Everything I read online said it was just part of the life cycle and that the plant was coming to the end of the bloom cycle. I kept watering and kept sunning and eventually I saw what looked like new growth at the end of the main stem as well as a little growth at the strongest branch. Well the growth has since stopped and now there's not a whole lot going on.

However over the last few days the bottom most leaf is starting to turn yellow. I still have 4 big leaves that appear to be healthy. A small branch off the main spike has also turned yellow all the way to the main spike.

So now I ask, what do I do next? Is the plan just done for a few months and I should trim the main spike back? If so, how far to I cut it and whats the best way to avoid infection or anything negative happening.

Thanks again for any help anyone can give. Feel free to ask any questions!