I think you've got a healthy plant there. Phal blooms can last for three or four months, but eventually they will drop, which is what yours is doing. The blooms will drop starting with the oldest and work up the stem. I think your yellowing leaf is normal too. It's the plant's oldest leaf; it's normal for a leaf to drop occasionally. As far as your blooms that won't "pop." I recently had the same issue. I gave the buds a little flick of the ole' snapper finger and they popped open for me, though I'm not sure what causes some flowers to not open fully. But it looks like you have some nice healthy roots and a well established plant. It's just ending its blooming cycle. You could always cut the stem back and see if you can get a rebloom, but if you are worried, I'd just cut the whole stem and let the plant rest until next time.