If the bubbles where clear then it wasn't lymphocyst.
It was either excess mucous and some airbubbles or some eggs attached to her back.
The lumps in the belly could be something she ate, parasitic worms or eggs developing inside her.
Check your water quality and make sure the gravel is nice and clean. Make sure the filter is running properly and see how it goes over the next few days. if it happens again look for fine air bubbles in the water. They could be coming from a leaky filter or an airstone.
A photo would be a big help.
Neons could have died from anything but if it happened over a short space of time, say 3 or 4 days, then it was probably a bacterial infection. The fish died and the b/nose ate them during the night. If the angelfish is big it might have eaten them too.
Anyway I'm going to bed so toodles all.