It sounds like your Hognose has a multitude of problems, all of which will require a trip to the veterinarian.
Aspen shavings is one of the better substrates for hognoses, it rarely causes problems unless you were to feed it inside of its tank. In the snake world, this practice is never recommended because of the potentials of ingesting (note: not in-digesting) the substrates which can cause an impaction (where the intestines are stopped up). Ideally, you would move the snake to a plastic container with absolutely nothing in it but the snake and its food. This problem alone may require surgical intervention to correct. There is no easy home remedy for this problem.
The swollen half of the mouth definitely indicates an infection, usually referred to as mouth rot, which can happen easily through any minor cut in the mouth. A cut can occur if it does ingest some of its substrates, or simply by the toenails of a mouse. This problem would require a diagnosis by a veterinarian, cleaning and possible systemic antibiotics.
11 weeks without eating is longer than any of us like to get used to, no matter how much hognoses are famous for. Hognoses are very robust snakes, if it does have wrinkles than I would expect it to be in the state of severe emaciation. It is critical that you get the snake to a veterinarian within the next week so that treatment can begin. Otherwise make sure the temperatures are within the correct range for hognoses and it is free from stress including high traffic areas and handling.
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...the oldest task in human history: to live on a piece of land without spoiling it."
Aldo Leopold (1938)
"Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us."
Calvin and Hobbes (Scientific Progress Goes 'Boink', 1991)
