Check your attorney client retainer. This contract defines your attorney's rights and your obligations. In general a PI attorney is entitled to his agreed upon percentage of 'all funds collected' on your behalf.
By answering your question we did not establish an attorney-client relationship. I have not examined all the facts or documents. I have not given you a legal advice nor intended to give you one on which you may rekly. A legal advice on which you can rely can only be given when all the facts are known and documents reviewed. My respoonse to your question was of a general educational nature. In order to obtain sopund legal advice you need tyo see an attorney who specializes or focuses in the area you are interested in.
From what you have said it is not clear that the attorney is taking a fee on the med pay. Most of us do not take a fee on med pay.
However, most state bars are now basically requiring that personal injury lawyers see that settlement or med pay money is used to pay off the doctor bills. In the "old days" the lawyer could agree with the client that it was the client's money and the client could pay or not pay the doctors as the client wished. No more.
I don't know about the rules in your state or what the fee contract provides, but I would NEVER claim a contingent fee on payment of uncontested first party insurance such as medpay coverage. If this were in Georgia you could call the Consumer Affairs office at the State Bar. Fee arbitration may also be a possibility if he insists on claiming a fee on an uncontested first party insurance payment. See http://www.calbar.ca.gov/Attorneys/LawyerRegulation/ComplaintAlternatives.aspx
You havent provided enough info. I would need to know what if any auto ins you have on your own, or in your household.
If the accident was the drivers fault, you can sue him. His liability insurance limits are reduced by any med pay the carrier has paid. In that respect it may not be wrong for you atty to take a fee.
If you truly have a herniated disk due to this crash, your case may have significant value. You are not obligated to settle for the ins limits, but then the issue is the assets of the driver.
You dont make anatomical sense when you say you have l4-l7 levels in your back "messed up." There is no l7.
Im not sure you should be seeing a chiro, at this point. If you have herniations, you must be careful.
Your atty should be willing and able to sit down with you and explain everything. 25% is a bit lower than most attys charge. I dont know why your atty is charging less. He/she should still be willing to explain and do whatever is necessary to protect your interests and maximize your net recovery.