Wells scored 16 goals in 22 appearances for Bradford before being sold last week to Huddersfield, who paid a club record B£1.3million for the striker, while two more players sustained injury in the weekend's home game against Bristol City.
Parkinson was without midfielder Nathan Doyle (groin/hip), defenders James Meredith (foot) and Andrew Davies (knee), winger Raffaele De Vita (thigh), plus striker Andy Gray (dead leg) on Saturday and both Ricky Ravenhill (ankle) and Kyel Reid (calf) were forced out of the game.
"We've having a tough times with injuries at the moment," Parkinson said after his side's 1-1 draw.
"We've been relatively lucky with injuries since my time here - we have worked hard to prevent such problems - but unfortunately at the moment we've picked up a lot.
"It seems like we have picked up another couple, which is obviously a shame, but we have to stick together and show the commitment we have shown again in this match.
"With Nahki going, there was always going to be a degree of negativity around the ground because of the popularity of the player - you can't hide away from that.
"I spoke to the players about this and told them what could be expected in and around the ground. In fairness though, I felt our supporters were great and they really got behind the team."