Hi & Welcome,
You do not have PAWS. IF--and it is a big IF--you were to have PAWS the symptoms would not manifest until 6 months or more after stopping the drugs.
Twenty-one days is awesome but in terms of detox it is a short time. Your body is still healing so you need to give it time. Exercise will help. Eat right and push fluids. We abuse out bodies and minds for so long that we forget to take the time to heal.
Glad you found this site. Stick round--there is good support here.
Welcome and congratulations...21 days is a milestone. When I was detoxing I set 21 days as my first big goal.
As far as the on-going symptoms, it's all normal. As has been said on this forum many times, we put our minds and bodies through years of abuse, and then want to be normal NOW. I did. You are going to have to give it more time, but, like I said, 21 days is a turning point. You should start to feel better IF you are eating healthy and getting some exercise. You're not going to want to go to any big social event any time soon, but you do need to get out and take walks, etc.
I don't think that you should be experiencing really bad depression at this point; if it continues you probably should see a doc.
Be proud of what you've accomplished; keep posting.