I think you did exactly the right thing by filing and reporting your workers comp claim. In most states if you do not provide notice that you had an injury on the job within a very short period of time you will not be able to make a comp claim. Employers will somtimes even deny that it occured on the job at a later time. Employers are also required to report the injury to the insurance company and it is unethical and sometimes illegal for them not to do so.
With regard to the possibility that the chiropractor may have injured you, that would be covered by comp as well in most states because your employer told you to go to the chiropractor.
I would further highly recommend that you consult an attorney in your state specializing in workers compensation so that you can be sure to get the benefits to which you are legally entitled.
I agree with Joseph. You did the right thing by reporting the injury. I agree what your employer suggested was unethical and illegal. If the chiropractor aggravated your condition, it would still be part of the work injury, because the treatment was related to the work injury. To make sure your claim is processed correctly, and your rights are protected, I would suggest you get an attorney, whether my office or another workers' comp attorney licensed in PA.
Absolutely there is something you should do. You need an attorney right now. Your question has raised issues regarding entitlement, benefit rate and return to work issues at the very least. Please feel free to contact my office for a free consultation.
I would agree with Joseph, Glenn and James. You have nothing to feel bad about as you did nothing wrong. If you claim is accepted by the insurance carrier then you may want to consider having the paperwork reviewed by an attorney to make sure that everything is in order. If the claim is denied by the insurance carrier then you will need an attorney to file a Claim Petition.