Tendonitis

Ease off and change the focus of your climbing. If you've been chasing tiny crimpers up steep walls, go for bigger holds. If you've been going fast and hard, go slow and long. If you've been dynoing, practice your static moves. Get your head out of a rut and let your body heal and move on.

It usually takes a couple of days for muscles/tendons to recover from a hard workout. Use those days to work other muscles/tendons. Switch from overhangs to slabs. Do pushups. Go swimming. The older you get, the more important a varied workout is, because your recovery time lengthens.

Warmup. Stretch. Avoid *shock* loading your body. Rest.

...but that's just me...
Go see a doctor if the above doesn't make sense or work for you.