Not sure if I can be of much help but I will try until someone else comes. How were you giving fluids? The lump could be the crop and if you were giving fluids, it very well could be full of fluids. I would hold off on that for now if that is the case. According to what I have learned here, a baby does not really need much as far as food or water for a couple of days. You don't want to overfill the crop. (Or at least I would not think so). I had a couple that were weak like that and I gave a tiny bit of electrolytes a few times a day but not enough to fill up the crop. If it is the crop it should start going down if you don't push any more fluid for a while. If it goes down you will know. After the crop goes down some, you may want to try a little egg yolk, cooked of course. you can mix a little bit with a little water or electrolytes and give that in a s syringe without a needle. I push the plunger to make a bubble on the end and touch that to the beak of the chick. Do not push any more. Just a drop at a time and let the chick swallow. I guess you could use a dropper but be very carefull that you only let the chick get a drop at a time or it will drown. Hope that you have some luck and that your chick feels better soon.
Marie