i know for me that alcohol and drug addiction affected me in many ways you described. when i got clean and sober many of the syptoms you described lessened or went away. before that i felt hollow, isolated, felt doom and gloom and often felt no feelings at all, numb. was unable to even cry. in my case i would have been unable to even hold a job.
at the same time i treated my addictions i also was diagnosed with bipolar disorder leaning towards clinical depression. this by no means means you have my diagnosis of mental illness but i do suggest you run your symptoms by a doctor. most communities have free/low pay clinics if you can't pay much.
i also feel that your getting clean would greatly help. i don't know your drug of choice but there's narcotics anonymous and AA for you if you choose to stop using. both are free support groups.
it's good that you've made an attempt to help yourself but often times we need other's help too. when i did, it changed my life!!!
hope you'll keep us posted and know that we care.