Sgavallas, if tendonitis turns into tendonosis you are SCREWED. That will be the end.
Bicep tendonitis was in that tendonitis article I linked you.
On Tendonitis | Eat. Move. Improve.
Elbow problems can be due to shoulder problems. My elbows are that way, so I do quite a bit of shoulder mobility. I could probably do more but ehh, I'm functioning.
Get into the gym early and warmup your shoulders. I find straddle swings on rings loosen up my shoulders, hips and back very well.
Then I swing some dumbbells back and forth in front of me up and down like PBar swings (or you could just do some PB swings).
I use a rope to do pass throughs from in front of me to behind me. Like 10-15 times in over, under, and eagle grip. You can even do haloes where you circle it above your head one shoulder at a time.
You can also do some arm circles, big ones, littles ones, in front and back and across your body. Elbow circles, like 10-20 times in each direction.
Another good one is to get a small DB, like 3 or 5lbs and then stick your elbow in your ribs while keeping your forearm forward and parallel. Now twist from side to side slowly 15-25 times. You can also just use a stick and the longer the stick, the more leverage/force that you have to work against.
Another really good one is to hang on one arm and twist around. Generally, I would just have my little guys practice hang turns, 1/2s and full in all their grips. They think it's fun, it's actually for turn work and to loosen up their shoulders.
Cuban press - dumbbell - YouTube These are also really good for loosening up your shoulders. Again light weight (heck you can do it without a weight or hold like something light in your hands) and lots of reps. 15-25 maybe up to 50. Basically lots of reps to get motion of the joint and bloodflow in there (joints tend to have poor circulation).
If you have bands, you can also do these. If you don't have a pair of bands, you can do these exercises with light dumbbells or just without.
Basic Shoulder ROM and stabilization Routine - YouTube