Started counting calories and now my running sucks

With all the things you have listed that are doing physically, it sounds to me like your are over training (over working). Cut back on something and concentrate on your running.

This was my first thought too.

Even when you are doing a run-focused training program, they are not constantly building longer and faster with every workout. Fitness is built with cycles of stress and recovery. If you just stress stress stress all the time, your body never has a chance to build fitness.

Prioritize your goals.

You can't expect to perform optimally when you're eating in a calorie deficit.

If you want to do your best at the tough mudder then eat for it. Once you're done with it then you can start eating at a deficit to lose weight again.

Dirty Diana wrote...

THIS... is bologna. You can absolutely run on a small deficit and still perform well. People do it all the time. I've done it myself. Losing 2 pounds in a week and feeling like crap just means your deficit is too large at this point. I would suggest adding 500-750 calories a day and you should start to feel better and still see some movement on the scale. If you can, I'd also suggest getting some kind of fitness tracking device (I use a Fitbit) to help you see how many calories you're actually burning in a day. Most people tend to overestimate what they burn, but with all your activity, I'd guess you're underestimating.

Dirty D - you're almost right.

Howver....studies have shown that performance will suffer while losing weight (Lunn, Finn, and Axtell's work in 2009). The book referenced above in this thread by Matt Fitzgerald sites the studies of athletes where they took several groups and divided them up thusly for a 10 week training study...

Group 1 - added 2 x week sprint intervals to increase their power, but maintained their current weight
Group 2 - maintained their regular training, and actively pursued weight loss through dieting
Group 3 - added 2 x week sprint intervals to increase their power, and pursued weight loss through dieting
Group 4 - control group that maintained their current training and their current body weight

The group that saw the most performance increase was group 1 (gained 10% in performance). Of the two groups that pursued weight loss - group 3 - saw no performance increase due to, what Lunn refers to, as "inadequate protein intake kept their muscles from adapting to the stress imposed by the sprints"... .

Howver, group 2 saw a performance increase simply due to the weight loss making them lighter so their power to weight ratio was better than it was at the heavier weight.

The ideal time to lose weight and gain peformance is not leading right up into an event (such as the OP). So the posts suggesting to the OP to hold off on the weight loss until after this weekend may have a point depending on the OP's diet, and final 2-3 weeks of taper training into the event. And you may be correct in that a fine balance of losing the weight, yet fueling with enough protein to avoid muscle power performance loss could still allow the OP to trim some of the fat without a degradation in peformance.

At this point, it is probably moot with an event only 4 days away. The OP should focus on nutrient loading and recovery leading into the event to peak as best as they can for the best performance. It's the recovery where the most gains are made - and all the stress that the OP loaded onto her body with the final training should now be left to recover and build for this weekend.