The Social Security Administration has a very good web site, and this is a great place to start. As others have pointed out, you want to make sure this is a battle you wish to fight. If you have not worked enough years at a certain level of income, and your age is too low, you may not meet the criteria for any meaningful benefits. But if you do (or did) have a good income for a decade or more, and if you are of a certain age, then read the SSA Web Site.
If your physician believes you, she or he will often agree to show up at your Administrative Law Hearing. YOU get to pick your attorney, and even the City and State in which you wish to wage this battle. Normally when you see your physician, you are billed for ten- or fifteen-minute increments of time. A hearing will "blow away" half of a doctor's day of appointments, so make sure you are prepared to compensate them! Some states can have close to a year-long waiting list just to see the Administrative Judge. But I recommend using the system that is closest to your PHYSICIAN, especially if he or she will be there for you. Not having a physician present at your Hearing does not mean your claim is not a legitimate one, but having such a physician there to state your case will really HELP you. This is why it's best NOT to "doctor shop." The relationship you have with your doctor can be crucial. You'll be asking for ALL of your Medical Records, and this takes TIME. A good doctor will have a record of EVERY visit you have ever made. Your own records can be of immense help. The Administrative Law Judge will look at them.
Most (or maybe all) states allow SSD attorneys to collect a fee ONLY if you prevail in your case, and then these are highly regulated as to how much they can charge (maximum). But if you prevail, it will of course be worth it. These kinds of lawyers will not take you on if they feel your case is weak, so the fact that you find one who takes you is one third of the battle. And if you show up with a long history of good records, and a doctor and attorney, your chances are much better. The physician is the other third of the battle. It will take at least a year, probably closer to three years if all goes WELL and you prevail and get SSD and Medicare. The sooner you file, the sooner your "positive finding" can occur. Your own records and "story" is the final third of the battle.
Even if you do prevail, it is an exhausting process, and when I read my final judgement, I thought, "Wow, this guy is really ill." Being disabled is nothing to cheer about, and I'd really rather be working. If you can work at all, I would recommend having a long look in the mirror. Only you know the answer to this.
If you worked for many years and now you cannot, they will want to know WHAT CHANGED?! Pain itself is not sufficient criteria to receive an award. But Non-Exertional Limitations are taken into account. In other words, you might have the strength to do your occupation, but the pain may prevent you from being able to show up much of the time. This is taken into account, but must be thoroughly backed up by Objective Medical Evidence.
Lastly, if you have any other disability benefits, such as those from a former employer, they most likely will SUBTRACT ALL of your SSD award. This is to prevent "double dipping" and it shifts the burden from the Corporations to the Government. It's fairly common in many large Corporate Disability Agreements, all those silly papers you initial and sign when you begin any job. But it still can be "worth it" to have Medicare, which comes as a "tag along" with SSD, as it may become your Primary Insurance.
If you prevail, taxes will always be a NIGHTMARE, but if you prevail, this is sort of a good negative. I wish you the best in your pursuit. And regardless, Carry On! (jqt)