I'm currently having a problem with my reputation. The chat says it is 2484, but SE shows 2267 which seems to be wrong given the last uptades on the Q&As I've made. Any suggestions?
The rep that shows in Chat is your total reputation across the StackExchange network. Seeing that you have also a linked account at Physics and somewhere else, each with around 100 rep, I'd say that that's where the difference comes from.
(For example, my chat display shows almost 26K rep, whereas on Maths I only have arond 17K right now.)
Sometimes, reputation is "out of sync" due to deleted questions or other issues. You can find the most acccurate count by using something like this link. At the bottom, once per day, you can trigger a "reputation recalc", which will recompute your reputation to make it current. (You can trigger the recalculation once a day). The reputation syncs up every so often as the site does maintenance anywar.