For anyone reading this.
From personal experience, have a shower daily, go for a walk, even if it's only to the end of your garden or street and drink plenty of water. Sleep if you need to.
This won't fix things, but it will give you an opportunity to give yourself a break.
In my experience, beating yourself up about everything you suck at is the single biggest thing that made it worse for me.
Finally, talk to someone, anyone. In the street, at the bus, at work, friends, family, online, anyone.
This too will pass.