why doze my right testical pull into my body

There could be different reasons to it. Sometimes testicles just go up into the body cavity. This happens when it is cold, so that they can get warm. The reason the testicles are outside is that the body temperature is not appropriate for sperm production, so they stay out.
Like I said, when you are cold, or sometimes even during sex, the testicles may go up.
During sexual arousal certain muscles in the abdominal wall may contract to pull the testicles closer to the abdomen. This shouldn’t cause any pain but since you are experiencing some discomfort you should definitely see a doc.

Why does my right testicle go up inside my body when I am getting close to cumming? I am in my mid 50's, in good health.