Illness/Sickness: HELP swollen axy

I think that one of my axys sushi has swallowed a rock, she has a huge lump on her side that has only appeared in the last few hours, swallowing a rock is the only thing I can think of though I'm puzzled as the substrate is sand with some slate and a few big pebbles, the smallest pebble bigger than a 20p in diameter and about the same thickness, which is much bigger than her mouth, I made sure there were only big rocks and they are hurried in the sand just to give them a few hills. she's only a few month old, she's roughly 3 inches, she's still eating as normal but seems to be having a struggle swimming aboutis there anything I can do? I really can't see a way of her passing it, or a way that she managed to get it down in the first place, or any ideas on what else it could be? I will get some pictures first thing tomorrow. Thanks.

Without pictures..this may be difficult to diagnose. Try contacting a vet ASAP.

I agree, we need to see a picture. If you think it's a rock the best thing to do is have a vet take x-rays.