^^^^^^ your note implies that the hop onset was "all sudden like". Wierd, so I'd first suspect the fat tire. Is it still centered on the rim? Inspect the mold line all around. I'd even drop the pressure to about 10lbs and dribble the tire on a concrete floor. IOW bounce it then turn a bit and bounce again. Repeat all the way around. I find that this helps center a tire on a rim, especially one where the bead may be a bit large. Reinflate, spin and watch.
Othwise remove the tire n tube and put in the stand. You're into "wizards chess" now so good luck. Find the low spot (the flat section) and loosed 4 spokes. Go directly across the wheel and tighten 4 spokes. Check again. Repeat, breath, chant, groove to some tunes, repeat. If the rim is bent from hitting a rock or root you may not succeed. You may get lucky and round it again without over torquing some spokes.
Do do you still have the magic wand you bought in Diagon Alley. May need that.