I'm by no means a physical trainer or nutritionist, but...

First, congrats on 31 pounds!!!

Second, make sure you're getting enough water and protein in your diet. (I like to aim for 40% carbs, 30% fat, 30% protein.) Then evaluate your diet to see if you're missing any of the nutrients that make your skin happy, like vitamins E and B, biotin, etc. You can get those from food or a good quality supplement. A nice heavy duty moisturizing cream for your whole body will help, too. I have heard that the faster and more dramatic your weight loss is, the more time it will take for your skin to bounce back. If all else fails, you could see a dermatologist (skin doctor).

I think you are on the right track to do weight lifting! Good luck!!