First, what Arien said is a good start. More food, sweet potatoes/yams/starchy tubers PWO and all throughout the day.
Make a choice, stay in condition, or get bigger and get back in condition.
For just about everything you need to know when it comes to nutrition in order to grow, go here:
Interesting stuff in the second part on Paleo, which I am now kind of "meh" on regarding that everyone needs to eat Paleo or they'll die tomorrow:
Bottom line is that by going Paleo, you exclude a lot of foods. Not a bad idea if a lot of foods give you a problem. The problem though is that people equate Paleo with low carb eating, which is not a universal truth. When trying to be athletic, carbs are your friend and should be ingested at a rate consistent with your activity and goals. Don't discount the need to balance out your fat and eat enough protein, but carbs still get a bad rap.
Also, at your current weight assuming 4 workouts per week you'd need ~3000 cals to maintain current BW. Adding 500 cals/day to add 1lb per week (assuming you don't want to go with the GFH approach), you'd need 3500 just to start out. To maintain 220, you're in the neighborhood of 3300-3500 as a conservative estimate, using 15kcal/lb of bw as a baseline equation for maintenance. You may very well end up needing in excess of 4000 cal/day.