I quit drinking about 10 months ago. I am a recovering alcoholic whose daily caloric intake used to be roughly 5000 calories, 3000 coming in the form of beer. Since I have quit drinking I have gone from 6Ɖ" 210lbs to 6Ɖ" 170 lbs. I physicaly feel weaker.
I also have been having back pain and pain in my legs and butt. This is unrelated to the drinking but prevents me from doing the exercise I used to be accustomed to.
My appetite has also dwindled since I quit drinking and I probably only take in about 1600 calories a day now, and many of those are probably mpty caories from soda. The one good thing is I'd say what I do eat is a bit more balanced and almost completely fast food free.
Any help anyone can give me on how to put on weight in a healthy manner would be appreciated.

Have you seen a doctor/nutritionist? You sound undernourished, & need to compensate for the lost calories. Do you respect the 4 food groups? Veggies+Fruits / Grains / Poultry, Meat, Fish / Dairy? if you're not allergic
Soda is totally chemical toxic YuKBarf.
I bet if you eat a healthy breakfast N-R-Gize your day and a balanced diet, you'll be jammin in no time!
Also- what's your blood type? A, B, AB, O, etc Different blood types require different types of nutritional focus!