Not sure if it helps as its on a different part of the body but I get posterior tibial tendonitus which can come back if I don't keep an eye on what I do when I exercise (or even just day to day).
I worked out how to work around the pain, I worked out that certain exercises in certain ways meant I could carry on doing cardio instead of resting my entire body. I suppose what I was doing was working out without really working out the part of my body that was injured, it worked as the painful part never got irritated.
The next thing I did was work on what caused the problem, for me it was alot to do with my instep, it was unsupported as I ran on it meaning the muscles and ligaments in my calf were being pulled out of their comfort zone (and not in a good way). It meant I was injuring myself just by running and anything else high impact. I realised that I needed a new pair of trainers which suppoted my high instep and needed to get also a more supportive shoe for my gait then the ones I had been wearing.
Is there anything you feel may have caused your tendonitus? is there anything you can do to prevent your body making the same movements again- as this could prevent the pain returning.
And as always with an injury, RICE (Rest, Ice, Compression, Elevation) do this within the hour you have disturbed or worsened the pain for best results. It can help. Where elevation comes along it may be harder for you to do this as its on a central part of your body, so the idea is to reduce the blood flow (and so the swelling), see if you can lie down as this will help reduce your heart rate and so may help reduce the rate at which the blood pumps to the injury and so the swelling.
Drinking water goes without saying, Omega 3+6 oils can also help- they helped me anyway. Make sure you get the good quality stuff though as there are some brands out there not worth thier weight in salt let alone anything else!
Other then that, resting. Someone suggested massage to me with mine but to be honest with self massage at least I never felt any benefit.
