Medical exemptions, religious exemption or moral belief exemptions are all available to you. If your doctors records, or lack thereof, will not allow you to obtain a medical exemption, then either religious or moral exemption would be appropiate.

A paragraph is pasted here from this page: http://www.vaclib.org/legal/immigration.htm#immigration

Form I-601, including instructions, may be accessed at:

       INS Form I-601
     ... I-601, Application for Waiver of Ground of Excludability. ...
This version of the I-601, an Application for Waiver of Ground of Excludability, is a fillable form. ...       http://www.ins.usdoj.gov/graphics/formsfee/forms/i-601.htm - 13k -

       http://www.ins.gov/graphics/formsfee/forms/files/i-601.pdf
This is a 187K PDF file including both a fillable form and instructions.