Poor old Cakedog vomited today, which is highly unusual for him. This was around lunchtime, and since then he's been getting progressively more lethargic and looking just generally poorly and sorry for himself.
Has now taken himself off to bed, and isn't interested in waking up and interacting with us - extremely unusual; he's a 14 month springer.
My immediate thought was that he's eaten something which has disagreed with him, as he tends to eat all sorts of crap when we're out walking.
Then I remembered that he'd had a tick, which we removed 6 days ago. I feel really awful, because it had been attached to his face for a couple of days before I realised what it was, as I'd never seen one before and this was completely new to me. I had thought that it was just a bit of 'stuff' in his fur, which I would get rid of when I brushed him. 
I'm pretty sure the tick was complete - it looked whole and horrid.
Now I'm panicking - is his illness tick-related? (Is the timescale right for this?)
What's my best course of action? Any advice would be very gratefully received!