The "pleasure of relief" in my mind is not pleasure - it is just relief.
Pleasure is for bodily sensations.
Enjoyment is for mental sensations
I would suggest "the feelings are two: pleasure and pain." Everything we feel is either pleasure or pain. It may be mild or intense, but it's either pleasure or pain. Relief is pleasure. Anxiety is pain. Enjoyment is pleasure. Happiness is pleasure. Aponia, ataraxia, khara (joy, exultation) , euphrosyne (mirth, good cheer, merriment), etc. are all pleasure. Take any "feeling" and it will fall somewhere on the scale of pleasure or pain. Even equilibrium or homeostasis is pleasure according to Epicurus. I personally am becoming more convinced that that is exactly what aponia and ataraxia are.