Quick Question – Advice Please!

I ran Tuesday morning (3.5 miles) and this morning (4.5 miles). Both runs were HARD. My legs feel like lead – so heavy & slow. This morning, my pace was about 12 minute miles, which is sloooooooowwwww for me on a level course (even my first mile, which is mostly downhill, clocked in at 11 minutes).

And now for the question, in two parts

1. Do you think this lead-legs is from a) the increase in other activities in the last week (biking + swimming), b) the fact that I ran my ass off in a half-marathon just under two weeks ago, or c) something else altogether

and

2. Since I do have a 20K trail race Sunday that I would like to finish without wanting to kill myself at the end, what do you think I should do with the next few days leading up to the race? I had planned

Today: morning run (done) & afternoon yoga
Friday: 6 mile run to & from pool, with swimming (about 1500 yds)
Saturday: 10 mile bike ride

I’m not worried about racing the 20K – it’s my first at that distance (so automatic PR) and it’s a trail race, so my goal was just to finish strong & have fun. But, since my 4.5 miles this morning sucked pretty hard, I’m not sure at this point that I could finish strong & happy….thoughts? advice?

Thanks in advance (brew review & corn chronicles this afternoon).