Both clubs look destined for Serie B next season with second-last Parma 11 points off safety with five games left, and Crotone two points behind.
A defeat would have seen the Calabrians mathematically demoted, instead they grabbed their first away win this season.
Lisandro Magallan nodded Crotone ahead after quarter of an hour in the Tardini Stadium.
Brazilian Hernani pulled Parma level 15 minutes later but Simy and Adam Ounas added two more before the break for the visitors.
Gervinho and Valentini Mihaila struck twice in eight minutes after the break for Parma to level at 3-3.
But a Yordon Osorio foul on Arkadiusz Reca saw the referee point to the spot and Simy slotted in the penalty to bring his tally to 19 league goals this season, and 12 in the last nine games.
“It’s a strange moment, I can’t be happy at 100 percent,” said the 28-year-old who is the third top scorer in Serie A behind Cristiano Ronaldo (25) and Romelu Lukaku (21).
“It’s true that on an individual level I’m doing well, but that’s not enough, what matters is the team, and we’re struggling.
“We deserved this victory for a long time. Now there are five games to go, we need to finish the championship in the best way possible.”
Eighth-placed Sassuolo kept their push for Europa League football alive with a 1-0 win over Sampdoria.
Domenico Berardi scored an acrobatic overhead goal on 69 minutes off a rebound after Samp defender Omar Colley had gotten in the way of his goal-bound header with the ball coming back to the Italy forward to finish off in style from close range with his back to goal.
Sassuolo stretched their winning streak to four games to move six points off Lazio in sixth position.
Sampdoria are ninth, 16 points off the European berths, with upcoming games against Roma and Inter Milan.
Earlier Genoa boosted their hopes of Serie A survival with a 2-0 win over Ligurian rivals Spezia, who still risk a return to the second-division.
Gianluca Scamacca and Eldor Shomurodov both came off the bench in the second half and scored to get the ‘Grifoni’ back winning after four matches.
Genoa move 13th, ahead of Fiorentina who host Juventus on Sunday, and are now eight points clear of the drop zone. Spezia are five points ahead of Cagliari who occupy the final relegation place.