"I ain't happy no mo'" (29)
The silver lining is that the singer has been happy in the past. If the blues is about loss, you have to a least had something to lose.
While the Weary Blues echoed through his head. (34)
"The Weary Blues" haunt the singer as he comes home and gets into bed. This is like work following you home. If you've ever dreamt about doing homework or taking a test, you get the idea.
He slept like a rock or a man that's dead (35)
Sure these are clichés, but rocking and death are mentioned earlier in the poem. Here is where the suffering ends. The singer put 110% of himself into "The Weary Blues" and it finally lets him get some rest as the sun begins to rise.