Shedding problems are usually humidity problems, and with it being winter, it makes sense that the humidity would be lower and possibly dip low enough to be a problem.

How & where are you measuring your temps & humidity? Those analog gauges can be inaccurate, and it is important that you aren't measuring it halfway up the side of the tank, for example, since your snake usually isn't halfway up the side of the tank.

Please tell us more history of the snake, such as how big/old it is, and whether or not it was feeding well for you before, or have you only owned it 3 months, etc.