The usual suspects are medications, lack of proper hydration, and lack of electrolytes. Age can also be a factor. Problems like this can come from the neck, do you have neck pain? I have this problem, it appears to be from a deteriorating cervical spine. Fixed it with physical therapy and rest but it comes back every time I went back to weight lifting so I had to stop. Rest for a few days, and if it doesn't go away, you might want to see a doctor to see if you have some nutritional deficiencies or something else going on. There's also a thing called biceps tendinitis. But I don't think anyone here can diagnose you over the internet.
Check into magnesium deficiency. Those are my go-to symptoms when I’m deficient.
Extra exercise, medications and supplements can all contribute.