I think we should slow down a bit.
You're currently at the fish store getting your water tested? Lets see what results you get from them; we can go from there.
No, I wouldn't try to feed it in the current state. It seems stressed. When was the last time you were stressed about something and was able to eat?

So no, don't feed. They are filter feeders, so, it will pick up some nourishment along the way.
Also, I think you should stop additives temporarily. Lets check your chemistry and make any necessary adjustments before we begin adding any product to the tank.
Also, I would set myself up with a water change station. It doesn't have to be big. 20% of your tank's total volume is between 2.5 and 3 gallons. I've always relied on 20% weekly water changes to keep my small tanks stable.