Euphorbia Trigona - weird spots

Hi,
I've had this succulent for over 2 years now. Today I was rearranging my lounge and found that on one side of this euphorbia trigona had these weird brown shiny spots. They weren't there a month ago when I watered him.
I water him only when dryed out complety.
I was wondering if this is really bad and do I need to chop him and start again or will they go away by themselves.... Or do I simply face his bad side to the wall?
Oh! And just resently all his leaves fell off.
I can't find any information online. Could anyone out there help a fellow grower out?
I'm desperate! Xx