Usually doctors have someone on call when they are out of town, is it possible that there may be someone covering for your doctors vacation? It is unfortunate that you were started on a new med and now are unable to consult your doctor. I would think a family practice primary care doctor would see you, if you explain your circumstances I think it is possible they could help you at least until your primary prescribing doctor is back.
If all else fails you can have an mental health evaluation done at the ER and they very well might help until you are able to be seen. I would certainly hope healthcare providers wouldn't only have the two options of: admitting you to psychiatric care in order to receive medication help or just tough it out.
If you are feeling like you can wait until the next business day, call around town to family practice/urgent care. If you are distressed and cannot wait, consult your local hospital ER. It wouldn't hurt to even just give a call and ask what the protocol is for mental health needs for your ER department.
Best wishes, I know it is a very difficult place to be in. Thinking of you and know you are not alone!