if I get knocked out and captured by the goblins, which is relatively easy to happen to me, as I suck at avoiding combats, I can't do anything at all. The one thing I can do is open a chest with a health upgrade, but aside from that, no interactions in the goblins cave 

That's my bad.  I didn't finish converting the goblin cave to use the new interaction system.  Most interaction in that area will require you to use the "c" key.