I had achilles tendonitis last year and subsequently had something called Shockwave therapy on it and it's fine now. If you google it you'll see what it does. Each session cost me £50 and I had maybe 5 blasts of it (can't remember exactly how many now) over about 3 months. I could still x train and it wasn't long before he told me to run on it again after may be a month or so because it then strengthen it.
Hope this helps (also having it again now for my hamstring tendonititis aaaaaarggh)
I've had this since end of May and not really run at all since (just cross training but no spinning or rowing). I've started having Shockwave therapy after it was diagnosed and had my second blast of shockwave yesterday. He says I'll probably need another couple of sessions of it (3 or 4 in total) and I've not to run till he says. It's getting a lot better but can still feel it when I kneel down so I know it's not gone yet.
See if you can find someone in your area who does Shockwave - it's £50 a time but well worth it as it makes it stronger and heals quicker.
I also had it on my left achilles last year and that's fine now so I know it works.
Its whats known as a referred pain. I'm currently suffering with it and it's coming from tight soleus (might not be spelt right!) calf muscle. Got to try and relax the muscle with massage, foam roller. voltarol the tendon, ice, not run for 10 days but can go on cross trainer.