My Phal has been blooming for a while now and the flowers is starting to die now, and I just realized this little bud just below where the last flower was. There is still three more flowers left on the plant.
I would like to know if it is another flower bud or could it possibly be a keiki?
Too soon to tell but I would say a sub spike , you can cut the spike above this new " bump " after all the flowers above has wilted. This will direct the growth hormones to this new sub spike which will give more flowers. If you see leaf like growth then its a keiki.
Looks like a bud for me, but it's difficult to be sure. You'll know soon enough.
Now I disagree with jai on cutting the spike. Leave it alone. The Phal will decide if the spike will die or not, or only partially die and dry. Once it's dry, cut the dry part.
Here's the thing if you don't cut the spike back to above this sub spike you may get a few more blooms from the end of the spike where some Phals will continue to produce a few more flowers however it MAY NOT!
Now that your Phal has started to sub spike if you cut above this growth it will have more energy to produce more and beautiful blooms.
I think it's a little early to tell whether it is a secondary spike or a keiki.
In my experience, secondary spikes are not as round as the one in the picture. When I've had a keiki grow on my spikes, they stared out as round mini leaves. While my secondary spikes start out as if they would if they were a primary spike, a mitten shape. Also a bit pointy.
You case is a bit strange because it looks like a single bud from the picture. What does the other side look like?