I think you need to go back one move with your FEN string, as it appears your Queen has already moved...?
He can't take your Queen with his pawn, because your Bishop on a6 will have him in check.
There's no point in him blocking with his c1 Bishop, because of Be3 Qxe3, Kf1 Qf2++...
...so all he has left is Kf1 Qh1+, Ke2 Qg2+, Ke1 Qf2++, just to drag it out one extra move :)
I think you need to go back one move with your FEN string, as it appears your Queen has already moved...?
He can't take your Queen with his pawn, because your Bishop on a6 will have him in check.
There's no point in him blocking with his c1 Bishop, because of Be3 Qxe3, Kf1 Qf2++...
...so all he has left is Kf1 Qh1+, Ke2 Qg2+, Ke1 Qf2++, just to drag it out one extra move :)