The 28-year-old frontman missed the win over Hull and the defeat at Leicester, but started Saturday's loss at Ipswich.
"With so many games and our training regime being so high intensity, little things like this happen," he said.
"It's not going to hinder on my career, it's just a strained muscle, there's other players more unfortunate."
Bothroyd returned for the 2-0 reverse at Portman Road despite having been sidelined for a fortnight, including sitting out any training sessions.
But the 6ft 3in player is confident he will be back somewhere closer to his usual form - which has seen him grab six goals already this season - for Saturday's midday clash with Millwall.
"I had a little grade one tear in my calf and calves can be a bit tricky sometimes," added Bothroyd who, in common with many other footballers, periodically suffers from problems to his triceps surae muscle group.
"I came into the game the other day [against Ipswich] and I think it was scheduled that I wasn't going to play the full game but I got near enough 80 minutes out of myself, so I was happy with that.
"Obviously the performance wasn't great from our team and the last couple of games haven't been good, but hopefully we can turn things around on Saturday and get back on track.
"Without training for a couple of weeks it's a bit much to ask, but I want to play every game.
"I've had a full week now of training and hopefully I'll be raring to go and sharp for Saturday."
Millwall come into the game on the back of a 6-1 home hiding by Watford.
"They lost heavily but... they're going to be no walkover, they're going to be a tough side, but if we go about it in the right way we can beat any team," Bothroyd added.
Cardiff are still expected to be without striker Craig Bellamy, while fellow frontman Michael Chopra is sidelined for at least the next two months after rupturing ankle ligaments.
Bluebirds boss Dave Jones is also likely to be without midfielders Seyi Olofinjana and Danny Drinkwater for the visit of Kenny Jackett's Lions.
Source: BBC Sport
Source: BBC Sport