Why am i tired all the time and have no energy or enjoy things i used to?

Illiness/depression: This could be a medical problem like anemia (low blood count) or low thryoid, or could be clinical depression. You really need to see a primary care provider to help sort out for you what might be going on.

Many possibilities: Some of the feeling could be coming from your oxycodone. Also you have the stress of chronic arthritis. That can also cause fatigue. If the problem is sleepiness especially sleepiness accompanied by insomnia then you may have a primary sleep disorder requiring a sleep evaluation. Low thyroid and many other medical and psychiatric problems and cause the symptoms as well. Please see your primary care practitioner for a proper evaluation and referral if necessary.Best wishes.