Hi there. My dd just cut her bottom two teeth and has gone back to her happy self. It was a tough couple of weeks, though. Teeth can make los extra-tired, their bodies are dealing with pain and that takes a toll on the system. Try shortening A times temporarily to see if that improves naps. Hyland's Teething Tablets are awesome too, they seem to take the edge off.
Sorry, hope things get better soon!