How can you check who gave you rep?

Also, I keep trying to give people rep that apparently I must've recently given to, and it won't let me. The rotation of actual members is dumb. The limit should be so many + reps to a member per time frame. Honestly, there is only like 2 or 3 people that I actually give rep to because they post good shit that I'M interested in, and they don't annoy me with stupid shit. However, by the contraints right now, I'm never going to be able to give rep to anyone else again unless I give it out to random people so I can restart the cycle....