I'm only 48, and haven't injured that particular tendon (yet). But I've had several other tendon problems (wrist, hip, shoulder).
My experience is that tendon healing time is on the order of months, not days. So you really want to work around it rather than waiting, if possible.
Maybe do a form check to see if you're doing something wrong? I was, that's what hurt my hips. My shoulders just needed a break from BB presses, I subbed DB presses and dips for a few months, they didn't aggravate my supraspinatus.
Static stretches and massage don't seem to help me. Frequent gentle movement (to circulate the synovial fluid and keep things warm) helps.