Discussion: Bollocks!

Rest is not the answer. See a physio and find out what the underlying cause is. AND get it properly massaged....(I do believe Anwen might be suitably qualified ;-)
This is how you lose your base....procrastination...
What cross training can be done achieving high HR?
What core, strengthening & stretching can be caught up with that ensures you bounce back better and faster?
Oh, and don't be tempted by the donuts ;-)

Rest is not the answer on its own! Like I said before get a massage - you no doubt had/have a little tear. In order to protect it is causing the cramping. This might have already healed into a scar but it needs broken down and got rid of! asap. get it smashed.

Were you ever scheduled to be racing BUCS this weekend? I'm not going to say that the course would 'suit you down to the ground', but it would definitely show up others' weaknesses more than yours.

unless there's a donut van next to it.

Nope, never. I played with the idea at one point but it didn't make sense to do another weekend of traveling.. I actually think I'm fitter on the flat hard stuff than I am on the soft hilly stuff at the moment but I suppose that is relative..

+1 on the travelling being the limiting factor.