Green Iguana help Please!?

Hey guys, I have decided to ask for help since I'm running out of thinking about this problem. I bought a green iguana yesterday, he/she is probably 12 inches long, healthy looking reptile. I have setup the cage just the way I have learned from 10000 sources. My tank is 30 gallons, may seem small but I think it's good for a year. I have a 100W basking light that is around 95-98 degrees during the day around the baskin. Humidity is low, around 40 if not 35. Today I noticed that he was running around the cage looking for a cool side plus the low humidity is killing him, he was going nuts today. I tried misting the cage couple of times a day, it temporary until it goes down again. I'm really confused about what I'm doing wrong here. There is a big branch that he cab climb on, a hidin;his bowl of food and water....coconut fiber substrate, and some plants.