Hi and welcome.
These are symptoms of nerve impingement and in your case it is most likely in the axilla where you are putting pressure by your crutches, pressing the nerve where it enters the arm. I would recommend you to use the crutches properly and use padded crutches.
Let me know if you have further questions.
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Wish you good health.
If these are elbow crutches then they can put pressure on the median and the ulnar nerve most likely the ulnar nerve, which has a very superficial course in and around the elbow joint. The best fix is to relieve the pressure from whichever site is being compressed, the elbow in your case.