Your son is probably being treated at Arrowhead Regional Medical Center. Unfortunately, ARMC won't release information to you about your son. They probably don't even have him listed as a patient, as inmates are often treated under pseudonyms.
You can try to contact the watch commander at West Valley Detention Center for information, but the jail often does not release medical information for security and privacy reasons.
If your son has designated a power of attorney, is married, or has a conservator, the person with the legal relationship to him may have more success in getting information or giving input into his treatment and care.
It is possible to bring in private medical personnel to provide treatment and care, in some cases. That personnel and treatment would be at your (or your son's) cost, and may be very difficult to organize.
If you hire an attorney to represent your son, that attorney will be able to visit your son in the hospital (so long as the doctors okay it) and get more information about his situation and treatment. He is entitled to an arraignment within 48hrs of his arrest, but his arraignment is likely to be postponed while he is in the hospital. Usually, the court will not appoint indigent defense counsel (ie the public defender) until he is present for arraignment. If the court does appoint a public defender while he is in the hospital, his PD can (and hopefully will) visit him.
Any statements I make in these forums (fora?) should not be taken as direct legal advice, merely informed guidance. This is true due to the anonymous nature of this venue, and the incomplete information which is invariably provided by the questions. It is imperative that you consult directly with an attorney regarding your specific situation before acting on or relying on anything represented here. Period.
I am so sorry for your situation! It is a terrible way the police handle these cases, but they are not going to give you information. I've had to help families in very similar situations deal with the fact that they could not go see their family member, or even get information on their status. It's very hard on the family, and frankly, not right! But, as Mr. Moore stated, your best bet is to hire an attorney who can see you son and check up on his situation. Arrowhead cannot keep the attorney from checking on your son, as that would be violating his right to counsel. Good luck!
The above stated is advice only, and does not establish an attorney-client relationship.