He doesn't look "skinny" to me either, but about those "wrinkles"- he looks like he's heading into a shed cycle to me, & that means you need to get that humidity UP quickly & keep it there until he gets done with his shed. When he's not in shed, humidity around 55% is okay, but in shed, 65-70% is best, ESPECIALLY because he's also battling mites- mites dehydrate a snake by sucking their blood- they're a health risk in many ways.