If it is achilles tendonitis (you may wish to get it diagnosed by a professional), achilles tendonitis sucks, so sympathies, but if no visible swelling at the pressure point, you will hopefully be able to get out of it relatively quickly and permanently. Suggest you figure out the underlying causes of the injury. You might be landing more on your fore-foot than mid-foot (Did you recently switch from a high drop (10mm+ to a low drop shoe?), increase your mileage by a lot quickly?) which may put too much load on your achilles if your calves are too weak-tight to take it.
Had this and fixed it in 2-3 months by: 3x15-20 eccentric heel drops 2-3x daily (or daily or every other day if your achilles-calves are too sore at first). For insertional (heel) achilles tendonitis, also do bent knee eccentric heel drops (Some rehab programs propose adding weight or increasing number of reps, especially for experienced high-mileage runners for whom 15 reps may be too easy to have an impact). Foam rolling morning and evening (rolling the tendon probably does not do much...work on the muscle). Cross-training on bike and elliptical (don't suggest running for the first 3-4 weeks, maybe longer depending on extent of your injury. You'll have to judge. I remember being afraid of going on my first run, but it worked out fine. You'll get there.).
Over a year and a half since my injury, no recurrence. I still do sets of 3x15-20 heel drops a couple times a week after easy runs for maintenance. Every pre-run warm-up includes heel walks, toe walks, side-foot walks, a few heel drops, ankle rolls in addition to other dynamic movements. I'm not in your mileage range (only 35-50mpw), but I'd say that kind of minimal maintenance is key to stay healthy.
I'd also say don't neglect the rest of your chain. It's all connected and a weakness here, creates and imbalance there,...so do your squats, etc..
Good article here which explains the why, what and how:
http://running.competitor.com/2014/12/injury-prevention/new-exercises-fixing-achilles-injuries_119928
Good luck!