Hi
It might be because of over straining your shoulder joint which seems like effecting your radial nerve which should be confirmed by neural tension tests done by a qualified physiotherapist.
Next Steps
need to evaluate how the shoulder joint is in relation to your working position.
selective stretching followed by strengthening of muscles should give you relief.
Health Tips
taping , splinting should be helpful. warm hot water bag application for 10 mins should give you immediate relief.
regards