started rooning 3 months ago,

I broke 28:40min 5k some time but my times seem to get worse and worse.
192cm and 82kg, at a calorie deficit since I want to lose some more weight (to 10% BF). am I overtraining, is it too much fatigue? I don't get it.

my speed increased to 4:30 paces but I have to take too many breaks. any advice?