A cut in the stem is expanding?
 

Good morning everyone, sorry for the not so clear title but I didn't know how to say it better.
I have a Phal that when I bought had a little cut on the outher layer of the stem. Never really had problems.
In the past week, above the cut, another one(?) has been developing, the two is possible to see by naked eye that are connected.

Took the highest resolution image I could.

Cut-On-Stem hosted at ImgBB — ImgBB

What would you say is happening?
Thanks!

Sometimes this happens when the environment is too dry and the plant doesn't absorb enough water (especially when is expanding which is a good indicator for this).

A photo of the whole plant (pot and medium included) would be important.

Here is a pic from above and side

Phal-From-Above hosted at ImgBB — ImgBB

Phal-From-Side hosted at ImgBB — ImgBB

Not sure about the enviroment being too dry, I watered and fertilized two days ago :(

The pot has 37 holes between the sides and bottom, to let it breath.

Environment being too dry is about humidity, not watering.

Aaaand this shows how much of a beginner I am. No idea about the humidity of my room...

The drier the environment is, the more water the plant loses by transpiration. This means you should increase watering frequency. This is amplified the the numerous holes in the pot, which is better than no holes at all. :)
How many times do you water it per week?
The madium seems to dry for a pot that has been waterd two days ago.

Since it's the only orchid I have, I weigh it every morning and when the weight decreases less than 3 grams from the day before, I water it. At the moment this happens usually a week after I water it. So yeah, I'm watering more or less once every 7-9 days

I suspect you should water it more.