I think what happened is that you deleted one or more posts of yours today, totaling 30 reputation points from upvotes (e.g. a +3 answer, a +6 question, or a mix of these) and -6 reputation points from downvotes (i.e. 3 downvotes). The deleted upvotes still count against the cap, because the deletion is not reflected in the counter that's used for the cap. The deletion of the downvotes, on the other hand, seems to have been reflected in the cap, so that you could get 6 points back, for a total of 186 (excluding acceptance rep which is not taken into account for the daily rep cap).
You should be able to make things right by recalculating your reputation from the real data. Your reputation total is normally not calculated from the real data, it's a running total that events like getting votes update. Some rare events such as deletions don't update that running total. Visit
/reputation to see a full audit of your real reputation. There's a button to
Trigger Reputation Recalc. If you press this button, your on-site rep will be the
total rep figure at the bottom of the
Note that a rep recalc may well decrease your rep, if you had a rep surplus (e.g. from now-deleted posts) that hadn't been properly taken into account. You can't do a recalc just for today, it's all or nothing.