Gopher Snake Won’t Poop or Musk

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I have had this gopher snake for 1 year now. It is currently almost 3 feet long. It has not pooped in atleast a month, I kept thinking that it would finally poop but it hasn’t. I have feed it a few times during this period. Today I held it for the longest time I’ve done. It then was getting ready musk on me but it almost looked like it was stuck. One side of the vent increased in size and the other side (the tail) which was normal size looked significantly smaller compared to how much larger the other side was. I am not sure what to do. Any advice?