About a year ago the back of my foot, about
Hello, I'm Dr. Branch, thanks for using Ask a Doctor. I suspect you are right that this pain is from your achilles tendon and that you have tendonitis. You have done some of the things that would be recommended acutely, such as taking Advil; putting ice on it can also help. Like you mentioned, avoiding aggravating activities, such as walking for you, will probably be necessary for it to heal. You can also get a heel lift to take some tension off the tendon, and taping it can also help (you can search for "taping for achilles tendonitis" or you can go to https://www.youtube.com/watch?v=E1BbGc9srkE to find instructions on how to do this).
Once the pain is starting to improve, it is also important to do some rehabilitation. WebMD has some exercises you can do that will help strengthen and stretch your achilles tendon, which may help with the pain and preventing you from hurting it again. One helpful video I've found is at https://www.youtube.com/watch?v=Y8Ag3Nbj98k, but there are many you can find on the internet.
Beyond that, sometimes doctors also give a shot of steroid to decrease the inflammation and pain, but this also has a risk of tendon rupture and depending on your age and how long you've had this pain, your doctor may not want to do it.
I hope that gives you some things to try that can help. Ultimately, you will likely have to rest it in order for it to heal, so you will have to decide it you can tolerate it or not. Either way, I hope it is feeling better soon, please let me know if you have any other questions and I would be glad to discuss it further with you.
Yes, most likely that is right. I think it would be reasonable to try the suggestions I gave first, as it is probably what you would be told if you went to the outpatient clinic. If after several weeks things aren't getting better, then it would probably be a good idea to get it looked at to make sure the diagnosis is right.