You gotta at least show the code for the :draw() function. There is no such thing as a "spritesheet" object in LÖVE or Lua, so there's no way for us to know what the problem is without seeing more of the code.
I don't know the signature of player.anim:draw, but if it's similar to love.graphics.draw, angle should be 0 rather than nil, and then the scale should come next. It looks like you're using 5 for horizontal scale, 1 for vertical scale, and -1 for origin X. That would explain the weird aspect of your image, I suppose.
Pgimeno, thanks you solved it. The tutorial I watched said that you only needed to fill in 1 scale parameter, which works most of the time, but I guess if you put in parameters after the scale parameter, it messes things up. I filled both the sx and sy parameters and now it works. Thanks!