Being a beginner myself, I can't help you with the spots, but more experienced members will.
I think you need to cut off the old spike and pull the Phal. out of the pot to get a good look at the roots. Roots that are soft, mushy and/or black, need cutting off, because they are rotten. Put a little cinnamom (yes, the spice) on the cuts only. After cutting off root mass, you most likely need a smaller pot to put the plant in, with fresh bark. Most people presoak the new bark for about 24 hrs, so it absorbes the future waterings better.
I have all my orchids in clear plastic pots with good drainage, so I can see what's going on with the roots. I also put a wooden skewer down into the bark and pull it out periodically to check the moisture. If the skewer is dry or almost dry, it's time to water.
All of the above I have learnt here on the Board from members and it has served me well.
THANK YOU one and all!
oops, just saw that you cut the spike already