Awww honey, don't feel stupid.
I've had this in the past to a certain degree, I have a problem with seretonin levels in my head, i suppose a sort of lifelong clinical depression in a way.
It can be very confusing and awful when it happens as there is no outward reason for it, just a chemical imbalance. I'm on medication now to correct it and which I will probably be on for life and things are much better :)
The best thing is to talk about it, the Samaritans are great if you want to speak to someone that way first.
http://www.samaritans.org.uk/
A good GP can also be a fantastic help, just be honest with them, don't be scared or embarrassed, as there are all sorts of ways they can help. Writing things down can help as it's always difficult to say what you want and everything you want when you're there. Maybe even send it to them in advance so you get more out of your appointment.
Can a friend or family member come with you? Maybe get a taxi door to door. Don't force things, if it's really bad ring and ask to speak to someone and explain your situation otthem and ask if it would be possible for someone to come out and see you.
There is a lot of help out there but you will also need to put a lot of effort in yourself for example going to appointments and collectiong any prescriptions which may help. There may be a period of trial and error to find what helps you best and it may take a while to feel better but if you try to help yourself and let others help you then you will get there honey.
If you feel any worse of have anymore harmful thoughts then your local casualty should have someone there you can talk to and where you can feel safer.
Hope this helps xxx