Help with vertex groups/weight painting

Hey guys, new to Blender. So I finished rigging my mesh and ran into some issues with weight painting. I get large, random vertex spikes and when I add/subtract to appropriate them to their correct respective bones it seems to cause more of them. Then when I fix the new spikes, the old ones reappear. Random vertexes on one arm of my model, for example, seem to be connected to the other arm, and the brushes can’t seem to fix it. Any suggestions?