Ask a Lawyer and Get Answers to Your Legal Questions
This is a civil rights issue and you need a civil rights attorney. The ACLU has branches all over the country. They do have a lot on their plate and may not be able to take on your son's particular plight but they should be able to direct you to an experienced civil rights lawyer in your part of the country who could be retained to assist your son.
Your son has the right to adequate medical care as an inmate. The US Supreme Court has held that a lack of adequate medical care is a form of cruel and unusual punishment, which makes it a violation of the 8th Amendment to the Constitution. The prison doesn't have to provide him with the same caliber of treatment that he can get on the outside. But they are not allowed to be indifferent to a life-threatening medical problem.
You can get an idea of what courts have found to be deliberate indifference and what sorts of situations constitute a serious medical need here in this PDF I am attaching.
It's been my experience that when an inmate needs medical treatment and isn't getting it, that family isn't going to be able to accomplish much by calling or emailing the prison. Generally, the authorities just give family the runaround and they won't address inmate care issues with them.
One thing you can do is to contact your son's lawyer and have him or her look into the matter. Lawyers can see an inmate without having to wait until visiting hours or days,which is more than what anyone else can do. They can see the shape the inmate is in. They can also get the case back in front of a judge, who can order medical treatment.
Here's the pdf.