First, teachers are not trained to handle many medical situations, and they are not required to be trained in all of the possible situations or conditions a special needs child may have. However, federal law (Section 504 of the Rehabilitation Act and the IDEA) requires that educational programs be made "accessible." The feeding of a child definitely falls into the accessibility category. You should immediately contact an experienced education attorney to work this matter out with the school. Good luck to you.
Mr. Mauro is correct. It is both not cost effective and in fact impossible to train teachers to handle every single possible disability that that may arise. BUT the school system is required to provide an equitable education for your son. You need to speak to school administration and if not satisfied, then speak to the school board and superintendent. You can also contact the Advocates for Children's Services which is the branch of Legal Aid of North Carolina that deals specifically with the rights of children.
Your son has a right to have his feeding needs met at school. The school has an obligation to meet his needs through his IEP or another plan such as a nursing plan. The feeding needs should be described in the IEP or other plan according to what is in the doctor's order. If you have not already resolved this issue then I would advise a progressively more aggressive approach. First, write to the school principal saying it is necessary to have an IEP meeting to discuss meeting your son's eating needs as without the school meeting them he cannot attend school. Do not "ask" for the IEP meeting. Rather, simply state the need for one. Give some possible dates and times. If the issue not resolved, write to the director of special education for your county, Christy Grant, asking her to resolve the issue. If this does not produce the desired result, consider a complaint with the state Department of Public Instruction (DPI). The complaint procedure and form is found in the link below. You are doing a great job advocating for your son so keep up the good work!