I have sprouts like that from time to time. Give it a couple weeks and it should straighten out. If not....cull.
Gnats! Damn.....
I recommend mosquito dunks in the water supply for the most natural, non-toxic method. Don't waste time with DE on top, or sand, or any of that. Get right on the mosquito dunks. They'll clear up soon enough.
For the next week or two, try to not let the top of the soil get most at all. Bottom water only. This will help kill the bastards.
Then, after the mosquito dunk has sat in your water supply for a week or two, top water with that. It's fine to just set aside 5 gallons of water and keep a dunk in it. Whatever you have to do.
Don't get too worried about the young one....they almost always straighten out.