How to cycle through animation loops in sequencer through player input?

Possibly (hopefully) a noob question.

Basically, I have 3 looping animations imported as a mesh cache. I’ve made 3 respective sequences containing each animation. I then put those 3 sequences in a master level sequence. When I press play, the three animations all play sequentially, which you would expect, but that’s not what I want.

What I want is for the first loop to actually loop constantly until the player presses a “go to next loop” button. At that time, the sequencer goes to the next loop, and loops that constantly until the player presses the button again, and so on until it reaches the last loop. When the player presses “go next” on the final loop, the whole thing goes back to the beginning of the first loop.

I would also like a “go previous” button that does the same thing in reverse order.

I feel like this should be a pretty simple thing to set up, but have been unable to find any information.

Please help!