You know when you feeling sad/lonely and you get pains in your chest and/or right arm
I get thems a lot
How do I turn them off?
Excercise and watch your diet. I've said this before. Attain homeostasis with a healthy diet and a routine rich in endorphines by excercising regularly. Homeostasis will be hard to attain since you in the extreme end where the brain has trained itself to attack your emotional state with hormones that reflect that state. You are producing lots of the "depressing" neurotransmitters and deregulating your hormonal stability. Be careful not to fall into a relapse.
Stop introspecting on your loneliness and do not feed your fantasy and imagination into producing more longings or crushes. This autohypnosis will throw your hormones into imbalance again. This is temporary and it will go away. It all depends on how long you decide to extend this period.
A psychiatrist will only go at your pace and try to find a lenitive solution. He feeds your ego, gives you pills, and steals your wallet. It will only take longer through that path. Follow my advice.
I agree with Mireille, I think it is better that you try solving that problem yourself...you shouldn't have to visit a shrink if you just feel sad because you're lonely. Instead try to do something against the loneliness and not the sadness