Defender Byron Anthony headed Rovers in front midway through the first half, but an own goal from Jeff Hughes saw Brighton level in the 62nd minute.
The Seagulls looked to be heading towards their seventh win in the last nine home league games when debutant Chris Wood, on loan from West Brom, converted a 73rd-minute penalty after Anthony had brought down substitute Glenn Murray, but Rovers snatched a share of the points in the second minute of stoppage time as a corner by Stuart Campbell was headed into his own net by Painter.
Trollope said: "We came to try and win the game and showed a fantastic work ethic throughout.
"We got pushed back in the second half and some of this was due to our own doing, but we showed a tremendous spirit to come back after Brighton had gone in front."
He added: "After a poor home defeat (3-0 at home to Orient) I would have taken 2-2 before the game."