"We played well in the first half, then Steve Evans took a knock," said Smith.
"He should have come off at half time but battled on because we're so short, then Neil Roberts was injured as well."
"We're in the midst of an injury crisis and it's causing a lot of problems," said Smith, whose side have plummeted down the table after losing six of their last seven.
"People say we should bring players in on loan but it isn't easy. I thought I had two lined up last week, but they fell through at the last minute.
"The injuries are frustrating, especially when we had such a good first half against MK Dons.
"We will improve and the squad will get stronger.
"We can play good football and we'll turn it around, but the manner of the loss on Saturday was disappointing."