Is every type of happiness or pleasure explainable (possible to articulate through reason or logic)? Should I be distraught that I am unable to articulate clearly some of my pleasures? And does an unexplainable pleasure (if it exists) suffer from its unexplainable nature or flourish because of it?

Your question has a number of facets. First of all, many theorists of emotions see them as complex rather than as simple entities, comprising at the very least a physiological dimension, a set of dispositions to behavior (including such things as facial expression and verbal behavior) and a phenomenology--a way that the emotion feels from the inside. Now it is pretty widely agreed that while the physiological and behavioral dimensions of any emotion can be described verbally, many would deny that we can put their phenomenology into words. After all, how would you explain how elation feels to someone who knows nothing of it, such as Mr. Spock? Yet if the "how it feels from the inside" dimension of it can't be articulated in words, then it seems that you're being hard on yourself in being distraught about being unable to articulate some of your pleasures. Likewise, if I can't articulate how one of my emotions feels, it is hard to see how that detracts in any way from the emotion--pleasure or...